criyle/codenet-compile-errors huggingface dataset:
Language: C++

#include<bits/stdc++.h>
using namespace std;
int c[26];
int main(){
    string s;
    for(int i=0;i<s.length();i++)c[s[i]-'a']++;
    for(int i=0;i<26;i++){
        if(c[i]==0){
            cout << ('a'+i);
            return 0;
        }
    }
    cout << "None"
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:19: error: expected ';' before '}' token
   13 |     cout << "None"
      |                   ^
      |                   ;
   14 | }
      | ~
Language: C++

#include<bits/stdc++.h>
using namespace std;
 
int main(){
  string s;
  cin >> s;
  for(char a = 'a'; a<='z'; a++){
    bool b = false;
    for(int i = 0; i<s.size(); i++){
      if(s.at(i) == a){
        b = true;
        break;
      }
    }
    if(!b){
      cout << a << endl;
      break;
    }
  }
  if(b)
    cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:20:6: error: 'b' was not declared in this scope
   20 |   if(b)
      |      ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  cin >> s;
  for(char a = 'a'; a<='z'; a++){
    bool b = false;
    for(int i = 0; i<s.size(); i++){
      if(s.at(i) == a){
        b = true;
        break;
      }
    }
    if(!b){
      cout << a << endl;
      break;
    }
  }
  if(b)
  cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:20:6: error: 'b' was not declared in this scope
   20 |   if(b)
      |      ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  cin >> s;
  bool b = false;
  for(char a = 'a'; a<='z'; i++){
    for(int i = 0; i<s.size(); i++){
      if(s.at(i) == a){
        b = true;
        break;
      }
    }
    if(b){
      cout << a << endl;
      break;
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:29: error: 'i' was not declared in this scope
    8 |   for(char a = 'a'; a<='z'; i++){
      |                             ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  cin >> s;
  bool b = false;
  for(char a = 'a'; i<='z'; i++){
    for(int i = 0; i<s.size(); i++){
      if(s.at(i) == a){
        b = true;
        break;
      }
    }
    if(b){
      cout << a << endl;
      break;
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:21: error: 'i' was not declared in this scope
    8 |   for(char a = 'a'; i<='z'; i++){
      |                     ^
Language: C++

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
using namespace std;
using P = pair<int, int>; 
using ll = long long;

int main()
{
  string s;
  cin >> s;
  map<char, int> mp;
  rep(i, n) mp[s[i]]++;
  char c;

  for(int i = 0; i < 26; i++) {
    c = 'a' - i;
    if(mp[c] == 0) {
      cout << c << endl;
      break;
    }
  }
  
  cout << "None" << endl;

  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:13:10: error: 'n' was not declared in this scope
   13 |   rep(i, n) mp[s[i]]++;
      |          ^
a.cc:2:45: note: in definition of macro 'rep'
    2 | #define rep(i, n) for (int i = 0; i < (int)(n); i++)
      |                                             ^
Language: C++

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
using namespace std;
using P = pair<int, int>; 
using ll = long long;

int main()
{
  string s;
  cin >> s;
  map<char, int> mp;
  rep(i, n) mp[s[i]]++;
  char c;

  for(int i = 0; i < 26; i++) {
    c = 'a' - i;
    if(mp[c] == 0) {
      cout << c << endl;
      break;
    }
  }
  

  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:10: error: 'n' was not declared in this scope
   13 |   rep(i, n) mp[s[i]]++;
      |          ^
a.cc:2:45: note: in definition of macro 'rep'
    2 | #define rep(i, n) for (int i = 0; i < (int)(n); i++)
      |                                             ^
Language: C++

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include<set>

int main()
{
    int n;
    std::cin >> n;
    std::vector<int> a(n);
    std::set<int> as;
    for (int i = 0; i < n; i++)
    {
        std::cin >> a[i];
        as.insert(a[i]);
    }

    auto itr = as.end();
    itr --;
    std::sort(a.begin(), a.end());
    std::vector<std::pair<int, int>> p(as.size());
    int n = as.size();
    int i = 0;
    while (1)
    {
        if (i >= n)
        {
            break;
        }
        int maxnum = std::upper_bound(a.begin(), a.end(), *itr) - std::lower_bound(a.begin(), a.end(), *itr);
        p[i].first = *itr;
        p[i].second = maxnum;
        itr--;
        i++;
    }

    long long ans = 0;
    long long h = 0;
    long long w = 0;
    int cnt = 0;
    for (int i = 0; i < n; i++)
    {
        if(p[i].second >= 4) {
            h = p[i].first;
            w = p[i].second;
            break;
        }
        else if (p[i].second >= 2)
        {
            if(cnt == 0) {
                h = p[i].first;
                cnt++;
            }
            else
            {
                w = p[i].first;
                break;
            }
        }
    }
    ans = h * w;
    std::cout << ans << "\n";
}



Compiler output:
a.cc: In function 'int main()':
a.cc:23:9: error: redeclaration of 'int n'
   23 |     int n = as.size();
      |         ^
a.cc:9:9: note: 'int n' previously declared here
    9 |     int n;
      |         ^
Language: C++

#include <bits/stdc++.h>
#include <vector>
#include <string.h>

using namespace std;

int main(){

  string s;
  cin>>s;

  char ani[24] = {'a','b','c','d','e','f','g','h','i','j',
                  'k','l','m','n','o','p','q','s','t','u',
                  'v','w','x','y','z'
   };

   sort(s.begin(),s.end());

   string das = "abcdefghijklmnopqrstuvwxyz";

   if(das == s){
    cout<<"None"<<endl;
  return 0;
   }

     for(int j=0;j<=24;j++)
     {
        int flag = 0;
     char news  = '1';
      for(int i=0;i<s.length();i++)
      {
        if(s[i] == ani[j]){
            flag = 1;
          break; }
          news = ani[j];
       }
        if(flag == 0 && news!= '1'){
        cout<<news<<endl;
        return 0; }

     }

     cout<<"None"<<endl;

return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:15:4: error: too many initializers for 'char [24]'
   15 |    };
      |    ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
      
int main(){
  string S;cin>>S;
  vector<int> vec(26,0);
  for(int i=0;i<S.size();i++){
    vec.at((int)S.at(i)-97)++;
  }
  int std;
  for(int j=0;j<26;j++){
    if(vec.at(j)==0){
      std=j;
      break;
    }
    else{
      std=-1;
    }
  }
  if(std>=0){
    k=std+97;
    cout<<(char)k<<endl;
  }
  else{
    cout<<"None"<<endl;
  }
  
}


Compiler output:
a.cc: In function 'int main()':
a.cc:21:5: error: 'k' was not declared in this scope
   21 |     k=std+97;
      |     ^
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
	string s;
    cin >> s;
    string t = abcdefghijklmnopqrstuvwxyz;
    for(int i=0;i<t.size();i++){
      int count = 0;
      for(int j=0;j<s.size();j++){
        if(t[i]==s[j]){
          count++;
        }
      }
      if(count == 0){
        cout << t[i] << endl;
        break;
      }
    }
    cout << "None" << endl;     
}


Compiler output:
a.cc: In function 'int main()':
a.cc:7:16: error: 'abcdefghijklmnopqrstuvwxyz' was not declared in this scope
    7 |     string t = abcdefghijklmnopqrstuvwxyz;
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~
Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<(n); i++)
using namespace std;

int main() {
  string S;
  cin >> S;
  for(char c='a'; c<='z'; c++) {
    bool found = false;
    for(int i = 0; i<S.length(); i++) {
      if(S[i] == c) found = true;
    }
    if(!found) {
      cout << c << endl;
      return;
    }
  }
  cout << 'None' << endl;
}

Compiler output:
a.cc:18:11: warning: multi-character character constant [-Wmultichar]
   18 |   cout << 'None' << endl;
      |           ^~~~~~
a.cc: In function 'int main()':
a.cc:15:7: error: return-statement with no value, in function returning 'int' [-fpermissive]
   15 |       return;
      |       ^~~~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string s1="abcdefghijklmnopqrstuvwxyz";
  string S;
  
  cin>>s1;
  cin>>S;
  sort(S.begin(),S.end());
 
  for(int i=0;i<S.size();i++){  
    for(int j=0;j<s1.size();j++){
      if( S[i]!==s1[j]){
        cout<<s1[j]<<endl; return 0;
      }else{
        cout <<"None"<<endl;
      }
    }
  }

return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:14:17: error: expected primary-expression before '=' token
   14 |       if( S[i]!==s1[j]){
      |                 ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<n; i++)

int main(){
  string word,alfabet;
  cin >> word;
  
  alfabet = "abcdefghijklmnopqrstuvwz";
  
  rep(i,word.size()){
    rep(j,alfabet.size()){
      if(alfabet[j] == wrod[i]) alfabet[j] = '0';
    }
  }
  
  int count = 0;
  
  rep(i,word.size()){
    if(word[i] != '0'){
      cout << word[i] << endl;
      break;
    }
    else count++;
  }
  
  if(count == word.size()) cout << "None" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:13:24: error: 'wrod' was not declared in this scope; did you mean 'word'?
   13 |       if(alfabet[j] == wrod[i]) alfabet[j] = '0';
      |                        ^~~~
      |                        word
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<n; i++)

int main(){
  string word,alfabet;
  cin >> word;
  
  alfabet = "abcdefghijklmnopqrstuvwz";
  
  rep(i,wrod.size()){
    rep(j,alfabet.size()){
      if(alfabet[j] == wrod[i]) alfabet[j] = '0';
    }
  }
  
  int count = 0;
  
  rep(i,word.size()){
    if(word[i] != '0'){
      cout << word[i] << endl;
      break;
    }
    else count++;
  }
  
  if(count == word.size()) cout << "None" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:9: error: 'wrod' was not declared in this scope; did you mean 'word'?
   11 |   rep(i,wrod.size()){
      |         ^~~~
a.cc:3:33: note: in definition of macro 'rep'
    3 | #define rep(i,n) for(int i=0; i<n; i++)
      |                                 ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<n; i++)

int main(){
  string word,alfabet;
  cin >> word;
  
  alfabet = "abcdefghijklmnopqrstuvwz";
  
  rep(i,wrod.size){
    rep(j,alfabet.size){
      if(alfabet[j] == wrod[i]) alfabet[j] = '0';
    }
  }
  
  int count = 0;
  
  rep(i,n){
    if(word[i] != 0){
      cout << word[i] << endl;
      break;
    }
    else count++;
  }
  
  if(count == word.size) cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:9: error: 'wrod' was not declared in this scope; did you mean 'word'?
   11 |   rep(i,wrod.size){
      |         ^~~~
a.cc:3:33: note: in definition of macro 'rep'
    3 | #define rep(i,n) for(int i=0; i<n; i++)
      |                                 ^
a.cc:12:19: error: invalid use of member function 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]' (did you forget the '()' ?)
   12 |     rep(j,alfabet.size){
      |           ~~~~~~~~^~~~
a.cc:3:33: note: in definition of macro 'rep'
    3 | #define rep(i,n) for(int i=0; i<n; i++)
      |                                 ^
a.cc:19:9: error: 'n' was not declared in this scope
   19 |   rep(i,n){
      |         ^
a.cc:3:33: note: in definition of macro 'rep'
    3 | #define rep(i,n) for(int i=0; i<n; i++)
      |                                 ^
a.cc:27:20: error: invalid use of member function 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]' (did you forget the '()' ?)
   27 |   if(count == word.size) cout << "None" << endl;
      |               ~~~~~^~~~
      |                        ()
Language: C++


#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main(){
    string s; cin >> s;
    vector<int> alphabet(26,0);
    
    //s内に一度でも出たらそのアルファベットを1にする
   rep(i,s.size()){
       alphabet.at(s.at(i) - 'a') = 1;
   }
   int i = 0;
   rep(i,25){
       if(alphabet.at(i) == 0);
       cout << itoa(97 + i) << endl;
   }
    cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:16: error: 'itoa' was not declared in this scope
   17 |        cout << itoa(97 + i) << endl;
      |                ^~~~
Language: C++

#include <iostream>
#include <algorithm>
#include <set>
using namespace std;

int main() {
  int S;
  char a[100010];
  cin >> S;
  for (int i = 0; i < S; ++i) cin >> a[i];

  char num[26] = {0};  // バケット
  for (int i = 0; i < S; ++i) {
      num[a[i]]++;  // d[i] が 1 個増える
  }
  int ans;
  for (int i = 0; i < S; ++i) {
    if(num[i]==0)ans=num[i];
    break;
    else std::cout << "None" << '\n';
  }

  cout << ans << endl;

}


Compiler output:
a.cc: In function 'int main()':
a.cc:20:5: error: 'else' without a previous 'if'
   20 |     else std::cout << "None" << '\n';
      |     ^~~~
Language: C++

#include <iostream>
#include <algorithm>
#include <set>
using namespace std;

int main() {
  int S;
  char a[100010];
  cin >> S;
  for (int i = 0; i < S; ++i) cin >> a[i];

  char num[26] = {'0'};  // バケット
  for (int i = 0; i < N; ++i) {
      num[a[i]]++;  // d[i] が 1 個増える
  }
  int ans;
  for (int i = 0; i < N; ++i) {
    if(num[i]=='0')ans=num[i]
    break;
    else std::cout << "None" << '\n';
  }

  cout << ans << endl;

}


Compiler output:
a.cc: In function 'int main()':
a.cc:13:23: error: 'N' was not declared in this scope
   13 |   for (int i = 0; i < N; ++i) {
      |                       ^
a.cc:17:23: error: 'N' was not declared in this scope
   17 |   for (int i = 0; i < N; ++i) {
      |                       ^
a.cc:18:30: error: expected ';' before 'break'
   18 |     if(num[i]=='0')ans=num[i]
      |                              ^
      |                              ;
   19 |     break;
      |     ~~~~~
Language: C++

#include<iostream>
#include<vector>
#include<string>
#define rep(i, n) for (int i = 0; i < (n); i ++)
using namespace std;

int main()
{
  string s;
  cin >> s;
  
  vector<int> a(26);
  int n = s.size();
  rep(i, n)
  {
    a.at((int)(s.at(i)) - 97) ++;
  }
  auto it = find(a.begin(), a.end(), 0);
  if (it == a.end()) cout << "None";
  else cout << distance(a.begin(), it);
  
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:18:17: error: no matching function for call to 'find(std::vector<int>::iterator, std::vector<int>::iterator, int)'
   18 |   auto it = find(a.begin(), a.end(), 0);
      |             ~~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/bits/locale_facets.h:48,
                 from /usr/include/c++/14/bits/basic_ios.h:37,
                 from /usr/include/c++/14/ios:46,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/streambuf_iterator.h:435:5: note: candidate: 'template<class _CharT2> typename __gnu_cxx::__enable_if<std::__is_char<_CharT2>::__value, std::istreambuf_iterator<_CharT> >::__type std::find(istreambuf_iterator<_CharT>, istreambuf_iterator<_CharT>, const _CharT2&)'
  435 |     find(istreambuf_iterator<_CharT> __first,
      |     ^~~~
/usr/include/c++/14/bits/streambuf_iterator.h:435:5: note:   template argument deduction/substitution failed:
a.cc:18:17: note:   '__gnu_cxx::__normal_iterator<int*, std::vector<int> >' is not derived from 'std::istreambuf_iterator<_CharT>'
   18 |   auto it = find(a.begin(), a.end(), 0);
      |             ~~~~^~~~~~~~~~~~~~~~~~~~~~~
Language: C++

 
char S[101010];
 
int main()
{
	scanf("%s", S);
 
	bool app[26];
	for (int i = 0; i < 26; ++i) {
		app[i] = false;
	}
	for (int i = 0; S[i] != '\0'; ++i) {
		app[S[i] - 'a'] = true;
	}
	for (int i = 0; i < 26; ++i) {
		if (!app[i]) {
			printf("%c\n", (char)(i + 'a'));
			return 0;
		}
	}
	puts("None");
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:9: error: 'scanf' was not declared in this scope
    6 |         scanf("%s", S);
      |         ^~~~~
a.cc:17:25: error: 'printf' was not declared in this scope
   17 |                         printf("%c\n", (char)(i + 'a'));
      |                         ^~~~~~
a.cc:1:1: note: 'printf' is defined in header '<cstdio>'; this is probably fixable by adding '#include <cstdio>'
  +++ |+#include <cstdio>
    1 | 
a.cc:21:9: error: 'puts' was not declared in this scope
   21 |         puts("None");
      |         ^~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string S;
  bool Alpha;
  cin >> S;
  for(int i=0;i<26;i++){
    Alpha[i]= false;
  }
  for(int i=0;i<S.size();i++){
    Alpha[S[i]-'a'] = true;
  }
  for(int i=0;i<26;i++){
    if(!Alpha[i]){
      cout << (char)(i+'a') << endl;
      return 0;
    }
  }
  cout << "None" << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:10: error: invalid types 'bool[int]' for array subscript
    9 |     Alpha[i]= false;
      |          ^
a.cc:12:10: error: invalid types 'bool[int]' for array subscript
   12 |     Alpha[S[i]-'a'] = true;
      |          ^
a.cc:15:14: error: invalid types 'bool[int]' for array subscript
   15 |     if(!Alpha[i]){
      |              ^
Language: C++

#include <iostream>

using namespace std;

int main(){
  string S;
  cin >> S;

  bool app[26];
  for(int i = 0; i < 26; i++){
    app[i] = false;
  }
  for(int i = 0; S[i] != '\0'; i++){
    app[S[i] - 'a'] = true;
  }
  for(int i = 0; i < 26; i++)}{
    if(!app[i]){
      cout << (char)(i + 'a') << endl;
      return 0;
    }
  }
  cout << "None" << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:30: error: expected primary-expression before '}' token
   16 |   for(int i = 0; i < 26; i++)}{
      |                              ^
a.cc: At global scope:
a.cc:16:31: error: expected unqualified-id before '{' token
   16 |   for(int i = 0; i < 26; i++)}{
      |                               ^
a.cc:22:3: error: 'cout' does not name a type
   22 |   cout << "None" << endl;
      |   ^~~~
a.cc:23:3: error: expected unqualified-id before 'return'
   23 |   return 0;
      |   ^~~~~~
a.cc:24:1: error: expected declaration before '}' token
   24 | }
      | ^
Language: Java

import java.util.*;

public class Main{
	
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	char[] a=sc.next().toCharArray();
    int e=0;
    for(char i='a';i<='z';i++){
      int f=0;
      for(int j=0;j<a.length;j++){
        
        if(ch[j]==i){
          f++;
          e++;
          break;
        }
      }
      if(f==0){
        System.out.println(i);
      }
    }
    if(e==0){
      System.out.println("None");
    }
  }
}


Compiler output:
Main.java:13: error: cannot find symbol
        if(ch[j]==i){
           ^
  symbol:   variable ch
  location: class Main
1 error
Language: Java

import java.util.*;

public class Main{
	
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	char[] a=sc.next().toCharArray();
    int e=0;
    for(int i='a';i<='z';i++){
      int f=0;
      for(int j=0;j<a.length();j++){
        
        if(ch[j]==(char)i){
          f++;
          e++;
          break;
        }
      }
      if(f==0){
        System.out.println((char)i);
      }
    }
    if(e==0){
      System.out.println("None");
    }
  }
}


Compiler output:
Main.java:11: error: cannot find symbol
      for(int j=0;j<a.length();j++){
                     ^
  symbol:   method length()
  location: variable a of type char[]
Main.java:13: error: cannot find symbol
        if(ch[j]==(char)i){
           ^
  symbol:   variable ch
  location: class Main
2 errors
Language: Java

import java.util.*;

public class Main{
	
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	char[] a=sc.next().toCharArray();
    for(char i='a';i<='z';i++){
      int f=0;
      for(int j=0;j<a.length();j++){
        
        if(ch[j]==i){
          f++;
          break;
        }
      }
      if(f==0){
        System.out.println(i);
      }
    }
  }
}


Compiler output:
Main.java:10: error: cannot find symbol
      for(int j=0;j<a.length();j++){
                     ^
  symbol:   method length()
  location: variable a of type char[]
Main.java:12: error: cannot find symbol
        if(ch[j]==i){
           ^
  symbol:   variable ch
  location: class Main
2 errors
Language: C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
  string s;
  cin >> s;
  
	bool app[26];
	for (int i = 0; i < 26; ++i) {
		app[i] = false;
	}
	for (int i = 0; s[i] != '\0'; ++i) {
		app[s[i] - 'a'] = true;
	}
	for (int i = 0; i < 26; ++i) {
		if (!app[i]) {
			cout << (char)(i + 'a')) << endl;
			return 0;
		}
	}
	cout << "None" << endl;
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:17:48: error: expected ';' before ')' token
   17 |                         cout << (char)(i + 'a')) << endl;
      |                                                ^
      |                                                ;
Language: C++

#include <bits/stdc++.h>
int main()
{
  string s;
  cin >> s;
  
	bool app[26];
	for (int i = 0; i < 26; ++i) {
		app[i] = false;
	}
	for (int i = 0; s[i] != '\0'; ++i) {
		app[s[i] - 'a'] = true;
	}
	for (int i = 0; i < 26; ++i) {
		if (!app[i]) {
			cout << (char)(i + 'a')) << endl;
			return 0;
		}
	}
	cout << "None" << endl;
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:4:3: error: 'string' was not declared in this scope
    4 |   string s;
      |   ^~~~~~
a.cc:4:3: note: suggested alternatives:
In file included from /usr/include/c++/14/string:41,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:5:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |   cin >> s;
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:10: error: 's' was not declared in this scope
    5 |   cin >> s;
      |          ^
a.cc:16:25: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   16 |                         cout << (char)(i + 'a')) << endl;
      |                         ^~~~
      |                         std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 |         cout << "None" << endl;
      |         ^~~~
      |         std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:27: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   20 |         cout << "None" << endl;
      |                           ^~~~
      |                           std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  bool a[26];
  string s;
  cin>>s;
  for(int i=0;i<26;i++){
    a[i]=false;
  }
  for(int i=0;i<s.size();i++){
    a[s[i]-'a']=true;
  }
  char b;
  for(int i=0;i<n;i++){
    if(a[i]=false){
      b=a[i];
      break;
    }
  }
  cout<<b<<endl;
}
  
  
  


Compiler output:
a.cc: In function 'int main()':
a.cc:15:17: error: 'n' was not declared in this scope
   15 |   for(int i=0;i<n;i++){
      |                 ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  bool a[26];
  string s;
  cin>>s;
  for(int i=0;i<26;i++){
    a[i]=false;
  }
  for(int i=0;i<s.size();i++){
    a[s[i]-'a']=true;
  }
  char b;
  for(int i=0;i<n;i++){
    if(a[i]=false){
      b=a[i]
      break;
    }
  }
  cout<<b<<endl;
}
  
  
  

Compiler output:
a.cc: In function 'int main()':
a.cc:15:17: error: 'n' was not declared in this scope
   15 |   for(int i=0;i<n;i++){
      |                 ^
a.cc:17:13: error: expected ';' before 'break'
   17 |       b=a[i]
      |             ^
      |             ;
   18 |       break;
      |       ~~~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  bool ad[26];
  string s;
  cin>>s;
  for(int i=0;i<26;i++){
    ad[i]==false;
  }
  for(int i=0;i<s.size();i++){
    ad[s[i]-'a']=true;
  }
  for(int i=0;i<26;i++){
    if(ad[i]=false){
      cout<<(char)('a'+i)<<endl;
      break;
    }
  }
  bool att=true;
  for(int i=0;i<26;i++){
    if(ad[i]=true){
      att=false;
      break;
    }
  }
  if(att) cout<<"None"<<endl;
}
}
  
    
  


Compiler output:
a.cc:29:1: error: expected declaration before '}' token
   29 | }
      | ^
Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for (int i=0; i<(n); i++)
using namespace std;

int main() {
  string s;
  cin >> s;
  int n = s.size();
  
  char ans;
  vector<int> moji(26,0);
  
  rep(i,n) {
    int temp = s[i]-'a';
    a[temp]++;
  }
  
  rep(i,26) {
    if (a[i] == 0) {
      ans = 'a' + i;
      cout << ans << endl;
      return 0;
    }
  }
  
  cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:5: error: 'a' was not declared in this scope
   15 |     a[temp]++;
      |     ^
a.cc:19:9: error: 'a' was not declared in this scope
   19 |     if (a[i] == 0) {
      |         ^
Language: C++

#include <bits/stdc++.h>

using namespace std;

int main()
{
    string S;
    cin >> S;

    vector<char> Alphabet = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
    vector<bool> v;
    vector<char> a;

    int flag = 0;

    for (int i = 0; i < Alphabet.size(); i++)
    {
        v.push_back(false);
    }
    for (int i = 0; i < S.length(); i++)
    {
        for (int a = 0; a < Alphabet.size(); a++)
        {
            if (S[i] == Alphabet[a])
            {
                v[a] = true;
            }
        }
    }

    for (int i = 0; i < v.size(); i++)
    {
        if (!v[i])
        {
            a.push_back(Alphabet[i]);
            flag = 2;
        }
        if (v[i])
        {
            flag = 1;
        }
    }

    if (flag == 1)
    {
        cout << "None";
    }

    if (flag == 2)
    {
        sort(a.begin(), a.end());
        cout << a[0];
    }

Compiler output:
a.cc: In function 'int main()':
a.cc:53:6: error: expected '}' at end of input
   53 |     }
      |      ^
a.cc:6:1: note: to match this '{'
    6 | {
      | ^
Language: C++

#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<math.h>
using namespace std;

int main(){
    string S;
    cin >> S;
    int num[150]={};
    sort(S.begin(), S.end());
    for(int i=0; i<S.size(); i++){
        num[(int)S.at(i)]++;
        //cout << (int)S.at(i) << endl;
    }
    for(int i=97; i<=97+25; i++){
        if(num[i]==0){
            cout << (char)i << endl;
            bool frag=true;
            break;
        }
        //cout << num[i] << endl;
    }
    
    if(frag==false){
        cout << "None" << endl;
    }
    
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:8: error: 'frag' was not declared in this scope
   27 |     if(frag==false){
      |        ^~~~
Language: Java

import java.util.HashMap;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		char[] S = sc.next().toCharArray();

		HashMap<Character, Integer> abcMap = new HashMap<Character, Integer>();
		for (char c : Const.alp) {
			abcMap.put(c, 0);
		}
		for (char c : S) {
			int value = abcMap.get(c);
			abcMap.put(c, ++value);
		}
		boolean None = true;
		for (int i = 0; i < Const.alp.length; i++) {
			int value = abcMap.get(Const.alp[i]);
			if (value == 0) {
				System.out.println(Const.alp[i]);
				None = false;
				return;
			}
		}
		if (None)
			System.out.println("None");
	}
}

Compiler output:
Main.java:12: error: cannot find symbol
		for (char c : Const.alp) {
		              ^
  symbol:   variable Const
  location: class Main
Main.java:20: error: package Const does not exist
		for (int i = 0; i < Const.alp.length; i++) {
		                         ^
Main.java:21: error: cannot find symbol
			int value = abcMap.get(Const.alp[i]);
			                       ^
  symbol:   variable Const
  location: class Main
Main.java:23: error: cannot find symbol
				System.out.println(Const.alp[i]);
				                   ^
  symbol:   variable Const
  location: class Main
4 errors
Language: C++

#include <bits/stdc++.h>
#include <iostream>
using namespace std;

int main(){
  string s;
  cin>>s;
  
  bool num[32];
  
  for(int i=0;i<26;i++){
    num[i]=false;
  }
  
  for(int i=0;s[i]!=null;i++){
    num[s[i]-'a']=true;
  }
  
  for(int i=0;s[i]!=null;i++){
    if(s[i]==true){
      cout<<s[i];
    }
  }
}


  
  


Compiler output:
a.cc: In function 'int main()':
a.cc:15:21: error: 'null' was not declared in this scope
   15 |   for(int i=0;s[i]!=null;i++){
      |                     ^~~~
a.cc:19:21: error: 'null' was not declared in this scope
   19 |   for(int i=0;s[i]!=null;i++){
      |                     ^~~~
Language: C++

#include <iostream>
using namespace std;

int main(){
  string s;
  cin>>s;
  
  bool num[32];
  
  for(int i=0;i<26;i++){
    num[i]=false;
  }
  
  for(int i=0;s[i]!=null;i++){
    num[s[i]-'a']=true;
  }
  
  for(int i=0;s[i]!=null;i++){
    if(s[i]==true){
      cout<<s[i];
    }
  }
}


  
  


Compiler output:
a.cc: In function 'int main()':
a.cc:14:21: error: 'null' was not declared in this scope
   14 |   for(int i=0;s[i]!=null;i++){
      |                     ^~~~
a.cc:18:21: error: 'null' was not declared in this scope
   18 |   for(int i=0;s[i]!=null;i++){
      |                     ^~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const ll MOD=1000000007;
const double PI=3.14159265358979;
const ll INF= pow(10,18);
typedef pair<ll,ll> P;
typedef vector<ll> vl;
typedef vector<vl> vvl;
#define FOR(i,a,b) for(ll i=a;i<b;i++)
#define rep(i,n) FOR(i,0,n)
string abc="abcdefghijklmnopqrstuvwxyz";
string ABC="ABCDEFGHIJKLMNOPQRSTUVWXYZ";

int main() {
  string s;
  cin >> s;
  ll k=s.size();
  ll cnt(26,0);
  rep(i,26){
    rep(j,k){
      if(s[j]==abc[i]){
        cnt[i]++;
      }
    }
  }
  ll X=-1;
  rep(i,26){
    if(cnt[i]==0){
      X==i;
      break;
    }
  }
  if(X==-1){
    cout << "None" << endl;
  }
  else{
    cout << abc[i] << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:19:14: error: expression list treated as compound expression in initializer [-fpermissive]
   19 |   ll cnt(26,0);
      |              ^
a.cc:23:12: error: invalid types 'll {aka long long int}[ll {aka long long int}]' for array subscript
   23 |         cnt[i]++;
      |            ^
a.cc:29:11: error: invalid types 'll {aka long long int}[ll {aka long long int}]' for array subscript
   29 |     if(cnt[i]==0){
      |           ^
a.cc:38:17: error: 'i' was not declared in this scope
   38 |     cout << abc[i] << endl;
      |                 ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  string s;
  cin>>s;
  int a[100005];
  int d=s.length();
  for(int i=0;i<s.length();i++){
    a[i]=(int)s[i];
  }
  sort(a,a+d);
  int f=1;
  if(a[0]==97){
  for(int i=0;i<d-1;i++){
    if(a[i]+1<a[i+1]){
      cout<<(char)(a[i]+1);
      f=0;
      return 0;

    }
  }
}else {
   cout<<'a';
   return 0;
}
if(f && a[n-1]!=122){
    cout<<'z';
}else{
  cout<<"None";
}


}



Compiler output:
a.cc: In function 'int main()':
a.cc:29:11: error: 'n' was not declared in this scope
   29 | if(f && a[n-1]!=122){
      |           ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  string s;
  cin >> s;
  for(char c='a';c<='z';c++){
    for(int i=0;i<s.size();i++){
      bool appear=false;
      if(s.at(i)==c){
        appear=true;
      }
    }
    if(!appear){
      cout << c;
      return 0;
    }
  }
  cout << "None";
}
        
      

Compiler output:
a.cc: In function 'int main()':
a.cc:13:9: error: 'appear' was not declared in this scope
   13 |     if(!appear){
      |         ^~~~~~
Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0;i < (n);i++)
using namespace std;
using ll = long long;
using pii = pair<int,int>;

int main(){
    string s;
    cin >> s;
    bool alp[26];
    rep(i,n){
        alp[i] = false;
    }
    rep(i,s.size()){
        alp[s[i] - 'a'] = true;
    }
    rep(i,26){
        if(!alp[i]){
            cout << char(i + 'a') << endl;
            return 0;
        }
    }
    cout << "None" << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:11: error: 'n' was not declared in this scope
   11 |     rep(i,n){
      |           ^
a.cc:2:37: note: in definition of macro 'rep'
    2 | #define rep(i,n) for(int i = 0;i < (n);i++)
      |                                     ^
Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0;i < (n);i++)
using namespace std;
using ll = long long;
using pii = pair<int,int>;

int main(){
    string s;
    cin >> s;
    bool alp[26];
    rep(i,n){
        alp[i] = false;
    }
    rep(i,s.size()){
        alp[s[i] - 'a'] = true;
    }
    rep(i,26){
        if(!alp[i]){
            cout << char(i + 'a') << ensl;
            return 0;
        }
    }
    cout << "None" << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:11: error: 'n' was not declared in this scope
   11 |     rep(i,n){
      |           ^
a.cc:2:37: note: in definition of macro 'rep'
    2 | #define rep(i,n) for(int i = 0;i < (n);i++)
      |                                     ^
a.cc:19:38: error: 'ensl' was not declared in this scope
   19 |             cout << char(i + 'a') << ensl;
      |                                      ^~~~
Language: C++

s = set(input())
l = list("abcdefghijklmnopqrstuvwxyz")
for i in s:
    l.remove(i)
if l == []:
    print("None")
else:
    print(l[0])

Compiler output:
a.cc:1:1: error: 's' does not name a type
    1 | s = set(input())
      | ^
Language: C++

#include <stdio.h>
#include <stdlib.h>

int	main()
{
	char	S[10001];
	int	*alpha;
	int	i, num;

	i = 0;
//	scanf("%s\n", S);
	gets(S);
	alpha = (int *)calloc(26, sizeof(int));
	while (S[i])
	{
		num = S[i] - 'a';
		alpha[num] = 1;
		i++;
	}
	for (i = 0; i < 26; i++)
	{
		if (alpha[i] == 0)
		{
			printf("%c\n", i + 'a');
			return (0);
		}
	}
	printf("None\n");
	return (0);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:9: error: 'gets' was not declared in this scope; did you mean 'getw'?
   12 |         gets(S);
      |         ^~~~
      |         getw
Language: C++

#include <iostream>
#include <string>
using namespace std;
int main(){
  string s; cin >> s;
  vector<bool> C(30,false);
  for(int i=0;i<s.length();i++){
  	C[s[i]-'a']=true;
  }
  string ans="None" ;
  for(char x='a';x<='z';x++){
  	if(C[x-'a']) continue;
    else {ans=x; break;}
  }
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:3: error: 'vector' was not declared in this scope
    6 |   vector<bool> C(30,false);
      |   ^~~~~~
a.cc:2:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
    1 | #include <iostream>
  +++ |+#include <vector>
    2 | #include <string>
a.cc:6:10: error: expected primary-expression before 'bool'
    6 |   vector<bool> C(30,false);
      |          ^~~~
a.cc:8:9: error: 'C' was not declared in this scope
    8 |         C[s[i]-'a']=true;
      |         ^
a.cc:12:12: error: 'C' was not declared in this scope
   12 |         if(C[x-'a']) continue;
      |            ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string S;
  cin >> S;
  int L=S.size();
  set<char> A;
  for(int i=0; i<L; i++){
    A.insert(S.at(i));
  }
  int Ans=0
  for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
    if(A.count(c)==0){
      Ans=1;
      cout << c << endl;
      break;
    }
  }
  if(Ans==0){
    cout << "None" << endl;
  }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:13:3: error: expected ',' or ';' before 'for'
   13 |   for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
      |   ^~~
a.cc:13:144: error: expected primary-expression before ')' token
   13 |   for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
      |                                                                                                                                                ^
Language: C++

#include<bits/stdc++.h>
using namespace std;

int main(){
  string S;
  cin >> S;
  int L=S.size();
  set<char> A;
  for(int i=0; i<L; i++){
    A.insert(S.at(i));
  }
  int Ans=0
  for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
    if(A.count(c)==0){
      Ans=1;
      cout << c << endl;
      break;
    }
  }
  if(Ans==0){
    cout << "None" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:13:3: error: expected ',' or ';' before 'for'
   13 |   for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
      |   ^~~
a.cc:13:144: error: expected primary-expression before ')' token
   13 |   for(char c:{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}){
      |                                                                                                                                                ^
a.cc:22:2: error: expected '}' at end of input
   22 | }
      |  ^
a.cc:4:11: note: to match this '{'
    4 | int main(){
      |           ^
Language: C++

def main():
    S = input()
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    flag = 0
    for c in alphabet:
        if S.count(c) == 0:
            print(c)
            flag = 1
            break
    if flag == 0:
        print("None")
main()

Compiler output:
a.cc:1:1: error: 'def' does not name a type
    1 | def main():
      | ^~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
typedef long long ll;
#define _GLIBCXX_DEBUG
typedef vector<int> vec;
typedef vector<ll> lvec;
typedef vector<char>cvec;
typedef pair<ll, ll> LP;
typedef tuple<ll, ll, ll> LT;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;
int main()	{
  string s;
  cin>>s;
  vector<int>d(26);
  rep(i,s.size()){
    d[s[i]-'a']++;
  }
  rep(i,26){
    if(d[i]==0){
      string a=d[i]-'a';
      cout<<a<<endl;
      return 0;
    }
  }
  cout<<"None"<<endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:24:20: error: conversion from '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   24 |       string a=d[i]-'a';
Language: C++

#include <bits/stdc++.h>
using namespace std;

int ans[26];
int main() {
  string s;
  cin >> s;
  for(int i=0;i<s.size();i++) {
    al[s[i]-'a']=1;
  }
  
  for(int i=0;i<26;i++) {
    if(al[i]==0) {
      cout << char('a'+i) << endl;
      return 0;
    }
  }
  cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:5: error: 'al' was not declared in this scope
    9 |     al[s[i]-'a']=1;
      |     ^~
a.cc:13:8: error: 'al' was not declared in this scope
   13 |     if(al[i]==0) {
      |        ^~
Language: C++

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
typedef vector<int> vec1;
typedef vector<string> vec2;
typedef vector<double> vec3;

int main() {
  
  string s;
  cin >> s;
  string a = "abcdefghijklmnopqrstuvwxyz";
  
  for(int i = 0; i < s.size(); i++) {
    for(int j = 0; j < a.size(); j++) {
      if(s.at(i) == a.at(j)){
        a.erase(a.begin() + j)
      }
    }
  }
  if(a.size() >= 1) {
    cout << a.at(0) << endl;
    return 0;
  } else {
    cout << "None" << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:31: error: expected ';' before '}' token
   17 |         a.erase(a.begin() + j)
      |                               ^
      |                               ;
   18 |       }
      |       ~
Language: C++

#include<iostream>
using namespace std;
int main(){
  char i;
  char* s;
  int k=0;
  
  cin >> s;
  for(i='a';i<='z';i++){
    if(i==s){
      cout << i;
      k++;
      break;}
    else{
    s++;}
  }
  
  if(k==0){
    cout <<"None";
  }
  return 0;
}
      

Compiler output:
a.cc: In function 'int main()':
a.cc:10:9: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
   10 |     if(i==s){
      |        ~^~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
int main(void){
    string S;
    cin >> S;
    sort(S.begin(),S.end());
    char x = 'a';
    for(int i = 0; i < S.size(); i++){
        if(S[i] == x) x++;
    }
    if('z' => x) cout << x << endl;
    else cout << "None" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:13: error: expected primary-expression before '>' token
   11 |     if('z' => x) cout << x << endl;
      |             ^
Language: C++

#include <iostream>
#include <string>
using namespace std;

int main(){
  	int S, N;
  	cin >> S;
  	N = S.size();
  	int a[26] = {0};
  	for (int i = 0; i < N; i++){
      	char p = S[i];
      	a[p - 'a']++;
    }
  	for (int i = 0; i < 26; i++){
      	if(a[i] == 0) cout << i + 'a' << endl;
    }
  	cout << "None" << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:8:15: error: request for member 'size' in 'S', which is of non-class type 'int'
    8 |         N = S.size();
      |               ^~~~
a.cc:11:19: error: invalid types 'int[int]' for array subscript
   11 |         char p = S[i];
      |                   ^
Language: C++

#include <iostream>
#include <string>

int main(){
  	int S, N;
  	cin >> S;
  	N = S.size();
  	int a[26] = {0};
  	for (int i = 0; i < N; i++){
      	char p = S[i];
      	a[p - 'a']++;
    }
  	for (int i = 0; i < 26; i++){
      	if(a[i] == 0) cout << i + 'a' << endl;
    }
  	cout << "None" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |         cin >> S;
      |         ^~~
      |         std::cin
In file included from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:7:15: error: request for member 'size' in 'S', which is of non-class type 'int'
    7 |         N = S.size();
      |               ^~~~
a.cc:10:19: error: invalid types 'int[int]' for array subscript
   10 |         char p = S[i];
      |                   ^
a.cc:14:23: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   14 |         if(a[i] == 0) cout << i + 'a' << endl;
      |                       ^~~~
      |                       std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:14:42: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   14 |         if(a[i] == 0) cout << i + 'a' << endl;
      |                                          ^~~~
      |                                          std::endl
In file included from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:16:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   16 |         cout << "None" << endl;
      |         ^~~~
      |         std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:16:27: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   16 |         cout << "None" << endl;
      |                           ^~~~
      |                           std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
typedef long long ll;
#define _GLIBCXX_DEBUG
int main()	{
  string s;
  cin>>s;
  vector<bool>ex(26);
  rep(i,26){
    bool ex[i]=false;
  }
  rep(i,s.size()){
    ex[s[i]-'a']=true;
  }
  rep(i,26){
    if(ex[i]=false){
      cout<<char(ex[i]-'a')<<endl;
      return 0;
    }
  }
  cout<<"None"<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:16: error: array must be initialized with a brace-enclosed initializer
   13 |     bool ex[i]=false;
      |                ^~~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
typedef long long ll;
#define _GLIBCXX_DEBUG
int main()	{
  string s;
  cin>>s;
  rep(i,26){
    bool ex[i]=false;
  }
  rep(i,s.size()){
    ex[s[i]-'a']=true;
  }
  rep(i,26){
    if(ex[i]=false){
      cout<<char(ex[i]-'a')<<endl;
      return 0;
    }
  }
  cout<<"None"<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:16: error: array must be initialized with a brace-enclosed initializer
   12 |     bool ex[i]=false;
      |                ^~~~~
a.cc:15:5: error: 'ex' was not declared in this scope; did you mean 'exp'?
   15 |     ex[s[i]-'a']=true;
      |     ^~
      |     exp
a.cc:18:8: error: 'ex' was not declared in this scope; did you mean 'exp'?
   18 |     if(ex[i]=false){
      |        ^~
      |        exp
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
typedef long long ll;
#define _GLIBCXX_DEBUG
int main()	{
  string s;
  cin>>s;
  vector<bool>c(26,false);
  rep(i,26){
    c[s[i]-'a']=true;
  }
  rep(i,26){
    if(c[i]==false){
      cout<<(char)(i+'a')<<endl;
      return 0;
  }
    cout<<"None"<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:2: error: expected '}' at end of input
   21 | }
      |  ^
a.cc:8:17: note: to match this '{'
    8 | int main()      {
      |                 ^