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

#include <bits/stdc++.h>
typedef long long ll;
#define _GLIBCXX_DEBUG
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define all(v) v.begin(), v.end()
using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;
const int INF = 1 << 30;
const ll INFll = 1ll << 60;
template <typename T>
bool chmax(T& a, const T& b) {
  if (a < b) {
    a = b;  // aをbで更新
    return true;
  }
  return false;
}
template <typename T>
bool chmin(T& a, const T& b) {
  if (a > b) {
    a = b;  // aをbで更新
    return true;
  }
  return false;
}

int main() {
  string O, E;
  cin >> O >> E;
  int len = O.length + E.length;

  int o = 0, e = 0;
  rep(i, len) {
    if (i % 2 == 0) {
      cout << O[o];
      o++;
    } else {
      cout << E[e];
      e++;
    }
  }

  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:31:15: error: invalid use of member function 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::length() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]' (did you forget the '()' ?)
   31 |   int len = O.length + E.length;
      |             ~~^~~~~~
      |                     ()
a.cc:31:26: error: invalid use of member function 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::length() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]' (did you forget the '()' ?)
   31 |   int len = O.length + E.length;
      |                        ~~^~~~~~
      |                                ()
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();
   char[] b = sc.next().toCharArray();

   StringBuilder ans = new StringBuilder();
   
   for(int i=0;i<b.length;i++) 
   {
     ans.append(a[i]);
     ans.append(b[i]);
   }
   if(a.length!=b.length) ans.append(a[a.length-1]);
   System.out.println(ans.toString);
 }
}

Compiler output:
Main.java:16: error: cannot find symbol
   System.out.println(ans.toString);
                         ^
  symbol:   variable toString
  location: variable ans of type StringBuilder
1 error
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define ll long long
typedef pair<ll,ll> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
#define M 1000000007
#define all(a) (a).begin(),(a).end()
#define rep(i,n) reps(i,0,n)
#define reps(i,m,n) for(int i=(m);i<(n);i++)
int main(){
  string s,t;
  cin>>s>>t;
  rep(i,min((int)s.size(),(int)t.size())cout<<s[i]<<t[i];
  if(s.size()>t.size())cout<<s[s.size()-1];
}

Compiler output:
a.cc:15:2: error: unterminated argument list invoking macro "rep"
   15 | }
      |  ^
a.cc: In function 'int main()':
a.cc:13:3: error: 'rep' was not declared in this scope
   13 |   rep(i,min((int)s.size(),(int)t.size())cout<<s[i]<<t[i];
      |   ^~~
a.cc:13:6: error: expected '}' at end of input
   13 |   rep(i,min((int)s.size(),(int)t.size())cout<<s[i]<<t[i];
      |      ^
a.cc:10:11: note: to match this '{'
   10 | int main(){
      |           ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define ll long long
typedef pair<ll,ll> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
#define M 1000000007
#define all(a) (a).begin(),(a).end()
#define rep(i,n) reps(i,0,n)
#define reps(i,m,n) for(int i=(m);i<(n);i++)
int main(){
  string s,t;
  cin>>s>>t;
  rep(i,min(s.size(),t.size())cout<<s[i]<<t[i];
  if(s.size()>t.size())cout<<s[s.size()-1];
}

Compiler output:
a.cc:15:2: error: unterminated argument list invoking macro "rep"
   15 | }
      |  ^
a.cc: In function 'int main()':
a.cc:13:3: error: 'rep' was not declared in this scope
   13 |   rep(i,min(s.size(),t.size())cout<<s[i]<<t[i];
      |   ^~~
a.cc:13:6: error: expected '}' at end of input
   13 |   rep(i,min(s.size(),t.size())cout<<s[i]<<t[i];
      |      ^
a.cc:10:11: note: to match this '{'
   10 | int main(){
      |           ^
Language: C++

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;

const int dx[4] = {-1, 0, 0, 1};
const int dy[4] = {0, -1, 1, 0};

// Self settings
// clang-format off
#define MAX_N 100000
#define REP(i, N) for (int i = 0; i < (int)(N); ++i)
#define SLN(i,N) (i == N-1 ? "\n" : " ")
ll fact(ll n) { ll res = 1; for(ll i=2;i<=n;++i) res = res * i; return res;}
ll nCr(ll n, ll r) {return (fact(n)/fact(n-r)*fact(r)) ;}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
const ll MOD = 1e9+7;
const ll INF = 1LL << 60;
const int inf = 1 << 30;
// clang-format on

string O, E;

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> O >> E;

  int i = 0, j = 0;
  while (i < O.length() || j < E.length()) {
    cout << (O[i] == '\0' ?  '' : O[i]);
    cout << (E[i] == '\0' ?  '' : E[i])
    if (i < O.length()) i++;
    if (j < E.length()) j++;
  }
  cout << endl;

  return 0;
}


Compiler output:
a.cc:45:30: error: empty character constant
   45 |     cout << (O[i] == '\0' ?  '' : O[i]);
      |                              ^~
a.cc:46:30: error: empty character constant
   46 |     cout << (E[i] == '\0' ?  '' : E[i])
      |                              ^~
a.cc: In function 'int main()':
a.cc:46:40: error: expected ';' before 'if'
   46 |     cout << (E[i] == '\0' ?  '' : E[i])
      |                                        ^
      |                                        ;
   47 |     if (i < O.length()) i++;
      |     ~~
Language: C++

#include <stdio.h>
int main()
{
    char a[50],b[50],c[100],m,k,i,s;
    scanf("%s",a);
    scanf("%s",b);
    k=strlen(a);
    m=strlen(b);
    s = k > m ? k : m;
    printf("%c%c",a[0],b[0]);
    for(i=1;i<=s;i++)
    {
        c[2*i-1]=a[i];
        c[2*i]=b[i];
    }
    for(i=1;i<=2*s;i++)
        printf("%c",c[i]);
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:7:7: error: 'strlen' was not declared in this scope
    7 |     k=strlen(a);
      |       ^~~~~~
a.cc:2:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    1 | #include <stdio.h>
  +++ |+#include <cstring>
    2 | int main()
Language: C++

#include <stdio.h>
int main()
{
    char a[50],b[50],c[100],m,k,i,s;
    scanf("%s%s",a,b);
    k=strlen(a);
    m=strlen(b);
    s = k > m ? k : m;
    printf("%c%c",a[0],b[0]);
    for(i=1;i<=s;i++)
    {
        c[2*i-1]=a[i];
        c[2*i]=b[i];
    }
    for(i=1;i<=2*s;i++)
        printf("%c",c[i]);
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:6:7: error: 'strlen' was not declared in this scope
    6 |     k=strlen(a);
      |       ^~~~~~
a.cc:2:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    1 | #include <stdio.h>
  +++ |+#include <cstring>
    2 | int main()
Language: C++

// BEGINNING WITH THE NAME OF ALMIGHTY GOD ALLAH
// AUTHOR:: MOHAMMAD FAISAL
#include<bits/stdc++.h>
using namespace std;
int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  
  string s;
  cin >> s;
  string t;
  cin >> t;
  int lenS = s.length();
  int lenT - t.length();
  
  for(int i=0;i<min(lenS,lenT);i++)
  {
    cout<<s[i]<<t[i];
  }
  if(lenS > lenT)
    cout<<s[lenS-1];
  if(len S < lenT)
    cout<<t[lenT-1];
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:12: error: expected initializer before '-' token
   16 |   int lenT - t.length();
      |            ^
a.cc:18:26: error: 'lenT' was not declared in this scope; did you mean 'lenS'?
   18 |   for(int i=0;i<min(lenS,lenT);i++)
      |                          ^~~~
      |                          lenS
a.cc:22:13: error: 'lenT' was not declared in this scope; did you mean 'lenS'?
   22 |   if(lenS > lenT)
      |             ^~~~
      |             lenS
a.cc:24:6: error: 'len' was not declared in this scope; did you mean 'lenS'?
   24 |   if(len S < lenT)
      |      ^~~
      |      lenS
a.cc:24:9: error: expected ')' before 'S'
   24 |   if(len S < lenT)
      |     ~   ^~
      |         )
a.cc:25:13: error: 'lenT' was not declared in this scope; did you mean 'lenS'?
   25 |     cout<<t[lenT-1];
      |             ^~~~
      |             lenS
Language: C

#include <stdio.h>
#include <string.h>

int main(void){
    char O[51],E[51];
    int i,size;
    scanf("%s",O);
    scanf("%s",E);
    size = strlen(O) + strlen(E);
    char ans[size];
    if(strlen(O) - strlen(E) == 0){
        for(i=0;i<strlen(E);i++){
            printf("%c",O[i]);
            printf("%c",E[i]);
        }
    }else{
        for(i=0;i<strlen(E):i++){
            printf("%c",O[i]);
            printf("%c",E[i]);
        }
        printf("%c",o[strlen(O) - 1]);
    }
    printf("\n");
    return 0;
}

Compiler output:
main.c: In function 'main':
main.c:17:28: error: expected ';' before ':' token
   17 |         for(i=0;i<strlen(E):i++){
      |                            ^
      |                            ;
main.c:21:21: error: 'o' undeclared (first use in this function)
   21 |         printf("%c",o[strlen(O) - 1]);
      |                     ^
main.c:21:21: note: each undeclared identifier is reported only once for each function it appears in
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
int main() {
  string a,b,c;
  cin >> a >> b;
  for(int i=0; i<b.size(); i++){
    c.pb (a.at(i));
    c.pb(b.at(i));
  }
  if(a.size() != b.size()) c.pb(a.at(i+1));
  cout << c << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:38: error: 'i' was not declared in this scope
   11 |   if(a.size() != b.size()) c.pb(a.at(i+1));
      |                                      ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
string s,t;cin>>s>>t;
for(int i=0;i<t.size();i++){
cout<<s.at(i)<<t.at(i); 
}
if(s.at(i)>t.at(i)) cout<<s.at(s.size())<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'i' was not declared in this scope
    8 | if(s.at(i)>t.at(i)) cout<<s.at(s.size())<<endl;
      |         ^
Language: C++

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
int main()
{
    char O[50];
    char E[50];
    char temp[100];
    gets(O);
    gets(E);
    int lo=strlen(O),i,j,c;
    int le=strlen(E);
    c=lo+le;
    for(i=0,j=0; i<c; i++,j++){
        temp[i]=O[j];
        temp[i+1]=E[j];
        i++;
    }
    temp[i]='\0';
        printf("%s\n",temp);

    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:10:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
   10 |     gets(O);
      |     ^~~~
      |     getw
Language: C++

#include<stdio.h>
#include<string.h>
using namespace std;
int main()
{
    char O[50];
    char E[50];
    char temp[100];
    gets(O);
    gets(E);
    int lo=strlen(O),i,j,c;
    int le=strlen(E);
    c=lo+le;
    for(i=0,j=0; i<c; i++,j++){
        temp[i]=O[j];
        temp[i+1]=E[j];
        i++;
    }
    temp[i]='\0';
        printf("%s",temp);

    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
    9 |     gets(O);
      |     ^~~~
      |     getw
Language: C++

#include<stdio.h>
int main()
{
    char A[50], B[50],c[100];
    int i,j;

    gets(A);
    gets(B);

    for(i=0,j=0;j<50 i++,j++)
    {
        c[i] = A[j];
        c[i+1] = B[j];
        i++;
    }
    puts(c);
}



Compiler output:
a.cc: In function 'int main()':
a.cc:7:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
    7 |     gets(A);
      |     ^~~~
      |     getw
a.cc:10:21: error: expected ';' before 'i'
   10 |     for(i=0,j=0;j<50 i++,j++)
      |                     ^~
      |                     ;
Language: C

#include<stdio.h>
int main()
{
    char A[50], B[50],c[100];
    int i,j;

    gets(A);
    gets(B);

    for(i=0,j=0;j<50 i++,j++)
    {
        c[i] = A[j];
        c[i+1] = B[j];
        i++;
    }
    puts(c);
}



Compiler output:
main.c: In function 'main':
main.c:7:5: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    7 |     gets(A);
      |     ^~~~
      |     fgets
main.c:10:21: error: expected ';' before 'i'
   10 |     for(i=0,j=0;j<50 i++,j++)
      |                     ^~
      |                     ;
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int i,x,y,z=2,sum=0;
	char a[50],b[50];
	gets(a);
	gets(b);
	x=strlen(a);
	y=strlen(b);
	for(i=0;i<x+y;i++)
	{
		if(z%2==0)
		{
			if(sum<x)
			{
				cout<<a[sum];
			}
			else
			{
				cout<<a[sum-x];
			}
		}
		else
		{
			if(sum<y)
			{
				cout<<b[sum];
			}
			else
			{
				cout<<b[sum-y];
				sum++;
			}
			sum++;
		}
		z++;
	}
	cout<<endl;
 	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:7:9: error: 'gets' was not declared in this scope; did you mean 'getw'?
    7 |         gets(a);
      |         ^~~~
      |         getw
Language: C++

#include <bits/stdc++.h>
#include <math.h>
using namespace std;
int64_t minn(int64_t a,int64_t b){
    if(a >= b) return b;
    else return a;
}
int main(){
    string O,E;
    cin >> O>>E;
   for(int i = 0;i < (O.size()+E.size()+1)/2;i++){
       if(E.size() = O.size() - 1 && i == (O.size()+E.size()+1)/2 -1 ){
       cout <<O[i];
       }
       else cout << O[i] << E[i];

   }
}




Compiler output:
a.cc: In function 'int main()':
a.cc:12:17: error: lvalue required as left operand of assignment
   12 |        if(E.size() = O.size() - 1 && i == (O.size()+E.size()+1)/2 -1 ){
      |           ~~~~~~^~
Language: C++

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

int main(){
  string o,e;
  cin>>o>>e;
  for(int i=0;i<e.size();i++){
    cout<<o.at(i)<<e.at(i);
  }
  if(o.size()-e.size()-==1){
	int sz=o.size()-1;
    cout<<o.at(sz);
  }
  cout<<endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:10:25: error: expected primary-expression before '=' token
   10 |   if(o.size()-e.size()-==1){
      |                         ^
Language: C++

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

int main()
{
	string s,t;
	cin>>s>>t;
	
	for(int i=0;i<s.length();i++)
	{
		cout<<s[i];
		if(i<t.length())
			cout<<t[i]
	}
	
	return 0;

}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:35: error: expected ';' before '}' token
   15 |                         cout<<t[i]
      |                                   ^
      |                                   ;
   16 |         }
      |         ~
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  int N,M;
  string O,E;
  cin >> O >> E;
  N = O.size();
  M = E.size();
  if(N > M){
   for (int i=0; i < N-1; i++ ){
          cout << O.at(i) << E.at(i);
      }
      cout << E.at(M-1) << endl;
  }
      if(N < M){
          for (int i=0; i < M-1; i++ ){
          cout << O.at(i) << E.at(i);
      }
      cout << O.at(N-1) << endl;
    }
    else if(N==M){
        for  (int i=0; i < N; i++ ){
          cout << O.at(i) << E.at(i);
   　　　}
      cout << endl;
  }
}


Compiler output:
a.cc:25:4: error: extended character 　 is not valid in an identifier
   25 |    　　　}
      |    ^
a.cc:25:4: error: extended character 　 is not valid in an identifier
a.cc:25:4: error: extended character 　 is not valid in an identifier
a.cc: In function 'int main()':
a.cc:25:4: error: '\U00003000\U00003000\U00003000' was not declared in this scope
   25 |    　　　}
      |    ^~~~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
    string O;
    cin >> O;
    string E;
    cin >> E;

    int A=O.size()
    int B=E.size()

if(A>B){
    for(int i=0; i<B; i++){
        cout << O.at(i) << E.at(i);
    }
    cout<<O.at(A);
}

else{
    for(int i=0; i<B; i++){
        cout << O.at(i) << E.at(i);
    }
    
}

    cout << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:5: error: expected ',' or ';' before 'int'
   11 |     int B=E.size()
      |     ^~~
a.cc:20:1: error: 'else' without a previous 'if'
   20 | else{
      | ^~~~
a.cc:21:20: error: 'B' was not declared in this scope
   21 |     for(int i=0; i<B; i++){
      |                    ^
Language: C++

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

int main() {
  int N,M;
  string O,E;
  cin >> O >> E;
  O.size() = N;
  E.size() = M;
  for (int i=0; i < N; i++ ){
      for(int j=0; i < M; j++){
          cout << O.at(i) << E.at(j);
      }
  }

}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: lvalue required as left operand of assignment
    8 |   O.size() = N;
      |   ~~~~~~^~
a.cc:9:9: error: lvalue required as left operand of assignment
    9 |   E.size() = M;
      |   ~~~~~~^~
Language: C++

#include <bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define all(a) a.begin(),a.end()
#define P pair<long long,long long>
#define double long double
using namespace std;
signed main(){
  string a,b;
  cin>>a>>b;
  if(a.size()==b.size()){
  rep(i,a.size())
  cout<<a.at(i)<<b.at(i);
    }
  else{
    rep(i,b.size())
      cout<<a.at(i)<<b.at(i);
    cout<<a.at(a.size-1);
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:18:18: 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 '()' ?)
   18 |     cout<<a.at(a.size-1);
      |                ~~^~~~
      |                      ()
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  string a,b;
  cin >> a >> b;
  for (i=0;i<b.size();i++){
    cout << a[i] << b[i];
  }
  if (a.size()>b.size()){
    cout << a[a.size()-1];
  }
  cout << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:8: error: 'i' was not declared in this scope
    7 |   for (i=0;i<b.size();i++){
      |        ^
Language: C++

#include<cstdio>
#include<isotream>
#include<cstring>
using namespace std;
    int a[60],b[60];
int main ()
{
    scanf("%s",&a);
    scanf("%s",&b);
    for(int i=0;i<=50;i++){
        if(a[i]!=0)cout<<a[i];
        if(b[i]!=0)cout<<b[i];
    }
    return 0;
}

Compiler output:
a.cc:2:9: fatal error: isotream: No such file or directory
    2 | #include<isotream>
      |         ^~~~~~~~~~
compilation terminated.
Language: C++

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

int main(){
 
  string o,e;
  cin>>o>>e;
 
  int oLen=o.size(),eLen=e.size();
 
  if(oLen==eLen) {
    for (i=0; i < oLen; i++) {
      cout<<o[i]<<e[i];
    }
  } else {
    for (i,i < eLen; i++) {
      cout<<o[i]<<e[i];
    }
    cout<<o[o.size()-1];
  }
  cout<<endl;
 
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:10: error: 'i' was not declared in this scope
   12 |     for (i=0; i < oLen; i++) {
      |          ^
a.cc:16:10: error: 'i' was not declared in this scope
   16 |     for (i,i < eLen; i++) {
      |          ^
a.cc:16:25: error: expected ';' before ')' token
   16 |     for (i,i < eLen; i++) {
      |                         ^
      |                         ;
Language: C++

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

int main(){
    string e;
    string o;
    int i, mx;
    cin >> o:
    cin >> e;
    
    if (o.size()==e.size()) {
        for (i=0; i < o.size(); i++) {
            cout << o[i] << e[i];
        }
    } else {
        i=0;
        while (i!=e.size()) {
            cout << o[i] << e[i];
            i++;
        }
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:13: error: found ':' in nested-name-specifier, expected '::'
    8 |     cin >> o:
      |             ^
      |             ::
a.cc:8:12: error: 'o' is not a class, namespace, or enumeration
    8 |     cin >> o:
      |            ^
Language: C++

#include<iostream>
#include<cstdio>
#include<string.h>
using namespace std;
int main()
{
	char a[51];
	char b[51];
	gets(a);
	gets(b);
	int len1=strlen(a);
	int len2=strlen(b);
	if(len1>len2)
	{
		for(int i=0;i<len2;i++)
		{
			cout<<a[i]<<b[i];
		}
		for(int i=len2;i<len1;i++)
		{
			cout<<a[i];
		}
		cout<<endl;
	}
	else
	{
		for(int i=0;i<len1;i++)
		{
			cout<<a[i]<<b[i];
		}
		cout<<endl;
	}
	return 0;
}

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

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
int main()
{
	char a[51];
	char b[51];
	gets(a);
	gets(b);
	int len1=strlen(a);
	int len2=strlen(b);
	if(len1>len2)
	{
		for(int i=0;i<len2;i++)
		{
			cout<<a[i]<<b[i];
		}
		for(int i=len2;i<len1;i++)
		{
			cout<<a[i];
		}
		cout<<endl;
	}
	else
	{
		for(int i=0;i<len1;i++)
		{
			cout<<a[i]<<b[i];
		}
		cout<<endl;
	}
	return 0;
}

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

#include<iostream>
#include<string.h>
using namespace std;
int main()
{
	char a[51];
	char b[51];
	gets(a);
	gets(b);
	int len1=strlen(a);
	int len2=strlen(b);
	if(len1>len2)
	{
		for(int i=0;i<len2;i++)
		{
			cout<<a[i]<<b[i];
		}
		for(int i=len2;i<len1;i++)
		{
			cout<<a[i];
		}
		cout<<endl;
	}
	else
	{
		for(int i=0;i<len1;i++)
		{
			cout<<a[i]<<b[i];
		}
		cout<<endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'gets' was not declared in this scope; did you mean 'getw'?
    8 |         gets(a);
      |         ^~~~
      |         getw
Language: C++

#include<iostream>
#include<string>

string a,b;
int i;

int main()
{
    std::cin>a>>b;
    for(;i<a.size()+b.size();i++)
        if(i%2)puts(a[i/2]);
        else puts(b[i/2]);
}

Compiler output:
a.cc:4:1: error: 'string' does not name a type; did you mean 'stdin'?
    4 | string a,b;
      | ^~~~~~
      | stdin
a.cc: In function 'int main()':
a.cc:9:14: error: 'a' was not declared in this scope
    9 |     std::cin>a>>b;
      |              ^
a.cc:9:17: error: 'b' was not declared in this scope
    9 |     std::cin>a>>b;
      |                 ^
Language: C++

#include<iosteam>
#include<string>

string a,b;
int i;

int main()
{
    std::cin>a>>b;
    for(;i<a.size()+b.size();i++)
        if(i%2)puts(a[i/2]);
        else puts(b[i/2]);
}

Compiler output:
a.cc:1:9: fatal error: iosteam: No such file or directory
    1 | #include<iosteam>
      |         ^~~~~~~~~
compilation terminated.
Language: C++

// --https://kenkoooo.com/atcoder/#/table/soma62jp
#include <iostream>
using namespace std;

int main(int argc, char* argv[]) {

	string O,E;

	cin >> O >> E;

	for (int i = 0; i < O.length(); i++) {
		cout << O[i];
		if(E.length()-1 > i){
			cout << E[i];
		}
	}

	cout << endl;

	return 0;


Compiler output:
a.cc: In function 'int main(int, char**)':
a.cc:20:18: error: expected '}' at end of input
   20 |         return 0;
      |                  ^
a.cc:5:34: note: to match this '{'
    5 | int main(int argc, char* argv[]) {
      |                                  ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  string a,b;
  cin>>a>>b;
  for(int i=0;i<a.size();i++)
    cout<<a.at(i)<<b.at(i);
  if(i==b.size())
    cout <<a.at(i);
}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:6: error: 'i' was not declared in this scope
    9 |   if(i==b.size())
      |      ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  string a,b;
  cin>>a>>b;
  for(int i=0;i<a.size();i++)
    cout<<a.at(i)<<b.at(i);
  if(a.size()==i+1 && b.size()+1==a.size())
    cout <<a.at(i);
}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:16: error: 'i' was not declared in this scope
    9 |   if(a.size()==i+1 && b.size()+1==a.size())
      |                ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  string a,b;
  cin>>a>>b;
  for(int i=0;i<a.size();i++)
    cout<<a.at(i);
  cout<<b.at(i);
  if(a.size()==i+1 && b.size()+1==a.size())
    cout <<a.at(i);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:14: error: 'i' was not declared in this scope
    9 |   cout<<b.at(i);
      |              ^
Language: C++

#include <bits/stdc++.h>

using namespace std;

int main() {
  string o;
  string e;
  cin >> o >> e;
  for (int i = 0; i < o.size(); ++i) {
    cout << o[i];
    if (i < e.size()) cout << e[i];
  }
  cout << endl;@
}

Compiler output:
a.cc:13:16: error: stray '@' in program
   13 |   cout << endl;@
      |                ^
Language: C

#include<stdio.h>

int main() {
	char G[51], K[51];
	scanf_s("%s%s", K, G);
	for (int i = 0; i < sizeof(K); i++) {
		printf("%c%c", K[i], G[i]);
	}
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:5:9: error: implicit declaration of function 'scanf_s'; did you mean 'scanf'? [-Wimplicit-function-declaration]
    5 |         scanf_s("%s%s", K, G);
      |         ^~~~~~~
      |         scanf
Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); i++)
#define rep1(i,n) for (int i = 1; i <= (n); i++)
#define repi(i,a,b) for (int i = (a); i < (b); i++)
#define all(x) (x).begin(),(x).end()
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using pii = pair<int, int>;
using vc = vector<char>;
using vvc = vector<vc>;
using vs = vector<string>;

int main() {
  string E, O; cin >> E >> O;
  rep(i,E.size()) {
    cout << E[i];
    if(i<O.size()) cout << o[i];
  }
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:28: error: 'o' was not declared in this scope
   21 |     if(i<O.size()) cout << o[i];
      |                            ^
Language: C++

#include <bits/stdc++.h>

#define ll long long
#define FOR(i,a,b) for (int i=(a);i<(b);++i)
#define REP(i,n) for(int i=0;i<(n);++i)
#define debug(x) cerr<<#x<<": "<<x<<'\n'

using namespace std;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef pair<int, P> PP;
typedef pair<ll, LP> LPP;

int dy[]={0, 0, 1, -1, 0};
int dx[]={1, -1, 0, 0, 0};

template<class T=int>
T in(){T x;cin>>x;return (x);}
template<class T>
void print(T& x){cout<<x<<'\n';}

const int MOD =(int)1e9+7;
const int MAX =510000;

ll fac[MAX],finv[MAX],inv[MAX];
void COMint(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for(int i=2;i<MAX;i++){
        fac[i]=fac[i-1]*i%MOD;
        inv[i]=MOD-inv[MOD%i]*(MOD/i)%MOD;
        finv[i]=finv[i-1]*inv[i]%MOD;
    }
}
ll COM(int n,int k){
    if(n<k) return 0;
    if(n<0||k<0)return 0;
    return fac[n]*(finv[k]*finv[n-k]%MOD)%MOD;
}


Compiler output:
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/14/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x17): undefined reference to `main'
collect2: error: ld returned 1 exit status
Language: C++

#include<iostream>
#include<map>
#include<set>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
#include<queue>
#include<stack>
#include<limits>
#include<sstream> 
#include<unordered_map>      

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef int itn;
typedef vector<int> vi;
typedef vector<ll> vl;

const int inf = numeric_limits<int>::max() >> 2;
const ll linf = numeric_limits<ll>::max() >> 2;
const ull ulinf = numeric_limits<ull>::max() >> 2;
const double pi = acos(-1);
const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};
const int dx8[8]={-1,0,1,-1,1,-1,0,1};
const int dy8[8]={-1,-1,-1,0,0,1,1,1};

#define p_queue(i) priority_queue<i> 
#define rp_queue(i) priority_queue<i, vector<i>, greater<i>> 
#define umap(i,j) unordered_map<i,j>
#define P(p) cout<<(p)<<endl
#define PS(p) cout<<(p)<< " "
#define IN cin >> 
#define rep(i,m,n) for(int i = (m); i < (int)(n); i++)
#define rrep(i,m,n) for(int i = (m-1); i >= (int)(n); i--)
#define inrep(n,a) for(int i = 0; i < (int)(n); i++)cin >> a[i];
#define mod(i) ((i)%(ll)(1e9 + 7))
#define divm(a,b) (mod(a * modpow((ll)b,(ll)(1e9+5))))
#define rsort(a,b,c) sort(a, b, greater<c>())
#define vsort(v) sort(v.begin(), v.end())
#define rvsort(v,c) sort(v.begin(), v.end(), greater<c>()) 
#define ft first
#define sd second
#define pb push_back
#define it insert
#define sz(x) ((int)(x).size())
#define lb(a,n,k) (lower_bound(a,a+n,k) - a) 
#define vlb(a,k)  (lower_bound(a.begin(),a.end(),k) - a.begin())
#define ub(a,n,k) (upper_bound(a,a+n,k) - a) 
#define vub(a,k)  (upper_bound(a.begin(),a.end(),k) - a.begin())
#define YES cout<<"YES"<< endl
#define NO cout<<"NO"<<endl
#define Yes cout<<"Yes"<<endl
#define No cout<<"No"<<endl  
#define yes cout<<"yes"<<endl
#define no cout<<"no"<<endl
#define ret return

ll modpow(ll i,ll j){ ll tmp=1; while(j){ if(j%2)tmp=mod(tmp*i);i=mod(i*i);j/=2;}return tmp;}
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

vector<string> split(const string &str, char sep){
    vector<string> v;
    stringstream ss(str);
    string buffer;
    while( getline(ss, buffer, sep) ) {
        v.push_back(buffer);
    }
    return v;
}

//ll ncr[100][100];
//ll nCr(int n, int r){if(n==r) ret ncr[n][r] = 1; if(r==0) ret ncr[n][r] = 1; if(r==1) ret ncr[n][r] = n;if(ncr[n][r]) ret ncr[n][r]; ret ncr[n][r] = nCr(n-1,r) + nCr(n-1,r-1);}

//ll npr[100][100]={};
//ll nPr(int n,int r){if(npr[n][r])ret npr[n][r];if(r==0)ret npr[n][r] = 1;if(r==1)ret npr[n][r] = n;ret npr[n][r] = n * nPr(n-1,r-1);}

//ll nHr(int n,int r){ret nCr(n+r-1,r);}

///////////////////////////////////////////////////////////////////////////


int main(){
    
    string o,e;
    cin >> o >> e;
    rep(i,0,min(sz(o),sz(e)))cout << o[i] << e[i];
    xif(sz(o) > sz(e))cout << o[sz(o)-1] << endl;
    else cout << endl;
    return  0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:92:5: error: 'xif' was not declared in this scope
   92 |     xif(sz(o) > sz(e))cout << o[sz(o)-1] << endl;
      |     ^~~
a.cc:93:5: error: 'else' without a previous 'if'
   93 |     else cout << endl;
      |     ^~~~
Language: C++

#include <bits/stdc++.h>
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,s,e) for (int i=s;i<(e);i++)
#define All(v) (v).begin(),(v).end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
using namespace std;
typedef long long llint;
typedef pair<int, int> P;
const int MOD = (int)1e9 + 7;
const int INF = 999999999;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    string O;
    string E;
    cin >> O >> E;
    REP(i,max(O.size(),E.size()){
        cout << O[i] << E[i];
    }
    cout << endl;
    
    return 0;
}

Compiler output:
a.cc:26:2: error: unterminated argument list invoking macro "REP"
   26 | }
      |  ^
a.cc: In function 'int main()':
a.cc:20:5: error: 'REP' was not declared in this scope
   20 |     REP(i,max(O.size(),E.size()){
      |     ^~~
a.cc:20:8: error: expected '}' at end of input
   20 |     REP(i,max(O.size(),E.size()){
      |        ^
a.cc:13:11: note: to match this '{'
   13 | int main(){
      |           ^
Language: C++

import Foundation

let o=readLine()!
let e=readLine()!

var res=""

for i in 0..<max(o.count, e.count){
    res+=String(o[o.index(o.startIndex, offsetBy: i)])
    if i<e.count{
        res+=String(e[e.index(e.startIndex, offsetBy: i)])
    }
}

print(res)


Compiler output:
a.cc:8:10: error: too many decimal points in number
    8 | for i in 0..<max(o.count, e.count){
      |          ^~~
a.cc:1:1: error: 'import' does not name a type
    1 | import Foundation
      | ^~~~~~
a.cc:1:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:15:6: error: expected constructor, destructor, or type conversion before '(' token
   15 | print(res)
      |      ^
Language: Java

import util.java.*;
 
public class Main {
	static Scanner scanner = new Scanner(System.in);

	public static void main(String[]$) {
		String[] a = new String[] {scanner.next(), scanner.next()};
		int length = a[0].length() + a[1].length();
		for (int i = 0; i < length; i++) {
			System.out.print(a[(i + 1) % 2].charAt(i / 2));
		}
		System.out.println();
	}
}

Compiler output:
Main.java:4: error: cannot find symbol
	static Scanner scanner = new Scanner(System.in);
	       ^
  symbol:   class Scanner
  location: class Main
Main.java:1: error: package util.java does not exist
import util.java.*;
^
Main.java:4: error: cannot find symbol
	static Scanner scanner = new Scanner(System.in);
	                             ^
  symbol:   class Scanner
  location: class Main
3 errors
Language: Java

import util.java.*;

public class Main {
	static Scanner scanner = new Scanner(System.in);

	public static void main(String[]$) {
		String[] a = new String[] {scanner.next(), scanner.next()};
		int length = a[0].length() + a[1].length();
		for (int i = 0; i < length; i++) {
			System.out.print(a[(i + 1) % 2].charAt(i / 2));
        }
		System.out.println();
	}
}

Compiler output:
Main.java:4: error: cannot find symbol
	static Scanner scanner = new Scanner(System.in);
	       ^
  symbol:   class Scanner
  location: class Main
Main.java:1: error: package util.java does not exist
import util.java.*;
^
Main.java:4: error: cannot find symbol
	static Scanner scanner = new Scanner(System.in);
	                             ^
  symbol:   class Scanner
  location: class Main
3 errors
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  string O,E;
  cin>>O;
  cin>>E;
  int o==0;
  int e==0;
  
  for(int i=0;i<O.size()+E.size();i++){
    if(i%2==0){
      cout<<O.at(o);
      o++;
      
    }
    else{
      cout<<E.at(e);
      e++;
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:8: error: expected initializer before '==' token
    7 |   int o==0;
      |        ^~
a.cc:8:8: error: expected initializer before '==' token
    8 |   int e==0;
      |        ^~
a.cc:12:18: error: 'o' was not declared in this scope
   12 |       cout<<O.at(o);
      |                  ^
a.cc:17:18: error: 'e' was not declared in this scope
   17 |       cout<<E.at(e);
      |                  ^
Language: C++

using namespace std;
#include <bits/stdc++.h>
#define rep(i, s) for (int i = 0; i < s; ++i)
#define repr(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define all(v) (v.begin(), v.end())
#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)
#define VEC(a, n) vector<int>a(n)
#define PQ(a) priority_queue<int>a
#define PQmin(a) priority_queue< int, :vector<int>, greater<int> >a
#define PAIR pair<int, int>
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
#define EPS (1e-7)
#define INF (1e10)
#define PI (acos(-1))
const ll mod = 1000000007;
 
int main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  string a,b;
  cin>>a>>b;
  string ans＝'a';
  if(a.size()==b.size()){
    rep(i,a.size()){
      cout<<a[i]<<b[i];
    }
  }
  else if(a.size()>b.size()){
    rep(i,b.size()){
      cout<<a[i]<<b[i];
    }
    FOR(i,b.size(),a.size()){
      cout<<a[i];
    }
  }
  else{
    rep(i,a.size()){
      cout<<a[i]<<b[i];
    FOR(i,a.size(),b.size()){
      cout<<b[i];
    }
  }
  cout<<ans<<endl;
  
  


}
     









Compiler output:
a.cc: In function 'int main()':
a.cc:25:15: error: expected initializer before 'a'
   25 |   string ans＝'a';
      |               ^~~
a.cc:46:9: error: 'ans' was not declared in this scope; did you mean 'abs'?
   46 |   cout<<ans<<endl;
      |         ^~~
      |         abs
a.cc:51:2: error: expected '}' at end of input
   51 | }
      |  ^
a.cc:20:11: note: to match this '{'
   20 | int main(){
      |           ^
Language: C++

#include<iostream>
#include<cstring>
using namespace std;
char a[101],b[101];
int blen;
int main()
{
    cin>>a>>b;
    blen=strlen(b);
    for(int i=0;i<l;i++)cout<<a[i]<<b[i]; 
    if(strlen(a)>strlen(b)) cout<<a[l]<<endl; 
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:19: error: 'l' was not declared in this scope
   10 |     for(int i=0;i<l;i++)cout<<a[i]<<b[i];
      |                   ^
a.cc:11:37: error: 'l' was not declared in this scope
   11 |     if(strlen(a)>strlen(b)) cout<<a[l]<<endl;
      |                                     ^
Language: C++

#include<iostream>
using namespace std;
int main(){
  string a,b;
  cin>>a>>b;
  vector<char> ans[100];
  for(int i=0;i<100;i++){
    ans[2*i]=a.at(i);
    ans[2*i+1]=b.at(i);
  }
  for(int i=0;i<a.size()+b.size();i++){
    cout<<ans[i];
  }
}
  

Compiler output:
a.cc: In function 'int main()':
a.cc:6:3: error: 'vector' was not declared in this scope
    6 |   vector<char> ans[100];
      |   ^~~~~~
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 | using namespace std;
a.cc:6:10: error: expected primary-expression before 'char'
    6 |   vector<char> ans[100];
      |          ^~~~
a.cc:8:5: error: 'ans' was not declared in this scope; did you mean 'abs'?
    8 |     ans[2*i]=a.at(i);
      |     ^~~
      |     abs
a.cc:12:11: error: 'ans' was not declared in this scope; did you mean 'abs'?
   12 |     cout<<ans[i];
      |           ^~~
      |           abs
Language: C++

#include <iostream>
using namespace std;

int main(){

  string E,O;

  cin>>E>>O;

  for ( int i = 0; i < E.size(); i++){

    cout << E [i];
  }


    if ( i < O.size()){
      

	 cout << O[i];
	 
	 }

    return 0;

  }


Compiler output:
a.cc: In function 'int main()':
a.cc:16:10: error: 'i' was not declared in this scope
   16 |     if ( i < O.size()){
      |          ^
Language: C++

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

int main(){

  string E,O;

  cin>>E>>O;

  for ( int i = 0; i < E.size(); i++){

    cout << E [i];


    if ( i < 0.size() cout << 0[i];
	 }

    return 0;

  }


Compiler output:
a.cc: In function 'int main()':
a.cc:15:14: error: unable to find numeric literal operator 'operator""size'
   15 |     if ( i < 0.size() cout << 0[i];
      |              ^~~~~~
a.cc:16:10: error: expected primary-expression before '}' token
   16 |          }
      |          ^
a.cc:15:36: error: expected ')' before '}' token
   15 |     if ( i < 0.size() cout << 0[i];
      |        ~                           ^
      |                                    )
   16 |          }
      |          ~                          
a.cc:16:10: error: expected primary-expression before '}' token
   16 |          }
      |          ^
Language: C++

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

int main(){

  string O,E;

  cin>>O>>E;

  std::wstring str1 = LO;

  std::wstring str2 = LE;
 
    size_t size1 = str1.length();
 
    size_t size2 = str2.length();


    for (int i = 0; i < size1:; i++){

      for (int j = 0; j < size2:; j++){

	if ( i % 2  = 0 ){

	  cout<<O<<endl;

	}

	else if ( j % 2 = 0 ){

	  cout << 0 <<endl;

	}

	cout<<endl;

      }

      cout<<endl;

    }

    return 0;
}
	


Compiler output:
a.cc: In function 'int main()':
a.cc:10:23: error: 'LO' was not declared in this scope; did you mean 'O'?
   10 |   std::wstring str1 = LO;
      |                       ^~
      |                       O
a.cc:12:23: error: 'LE' was not declared in this scope; did you mean 'E'?
   12 |   std::wstring str2 = LE;
      |                       ^~
      |                       E
a.cc:19:21: warning: range-based 'for' loops with initializer only available with '-std=c++20' or '-std=gnu++20' [-Wc++20-extensions]
   19 |     for (int i = 0; i < size1:; i++){
      |                     ^
a.cc:19:30: error: expected ';' before ':' token
   19 |     for (int i = 0; i < size1:; i++){
      |                              ^
      |                              ;
a.cc:19:36: error: expected ';' before ')' token
   19 |     for (int i = 0; i < size1:; i++){
      |                                    ^
      |                                    ;
a.cc:21:23: warning: range-based 'for' loops with initializer only available with '-std=c++20' or '-std=gnu++20' [-Wc++20-extensions]
   21 |       for (int j = 0; j < size2:; j++){
      |                       ^
a.cc:21:32: error: expected ';' before ':' token
   21 |       for (int j = 0; j < size2:; j++){
      |                                ^
      |                                ;
a.cc:21:38: error: expected ';' before ')' token
   21 |       for (int j = 0; j < size2:; j++){
      |                                      ^
      |                                      ;
a.cc:23:16: error: lvalue required as left operand of assignment
   23 |         if ( i % 2  = 0 ){
      |              ~~^~~
a.cc:29:21: error: lvalue required as left operand of assignment
   29 |         else if ( j % 2 = 0 ){
      |                   ~~^~~
Language: C++

#include<bits/stdc++>h>
using namespace std;
int main(){
  string O,E;cin>>O>>E;
  int M=O.size(),N=E.size();
  for(int i=0;i<N;i++)cout<<O.at(i)<<E.at(i);
  if(M>N)cout<<O.at(M);
  cout<<endl;
}

Compiler output:
a.cc:1:23: warning: extra tokens at end of #include directive
    1 | #include<bits/stdc++>h>
      |                       ^
a.cc:1:9: fatal error: bits/stdc++>: No such file or directory
    1 | #include<bits/stdc++>h>
      |         ^~~~~~~~~~~~~~
compilation terminated.
Language: C++

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

int main() {
  int O, M;
  cin >> O >> M;
  for(int i=0; i<M.size(); i++) {
    cout << O[i] << M[i];
  }
  cout << O[O.size()];
  return 0;
}
    

Compiler output:
a.cc: In function 'int main()':
a.cc:8:20: error: request for member 'size' in 'M', which is of non-class type 'int'
    8 |   for(int i=0; i<M.size(); i++) {
      |                    ^~~~
a.cc:9:14: error: invalid types 'int[int]' for array subscript
    9 |     cout << O[i] << M[i];
      |              ^
a.cc:9:22: error: invalid types 'int[int]' for array subscript
    9 |     cout << O[i] << M[i];
      |                      ^
a.cc:11:15: error: request for member 'size' in 'O', which is of non-class type 'int'
   11 |   cout << O[O.size()];
      |               ^~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  string O,E;
  cin >> O >> E;
  int a=O.size,b=E.size;
  for(int i=0;i<a;i++){
    cout<< O.at(i) << E.at(i);
  }
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:11: error: cannot convert 'std::__cxx11::basic_string<char>::size' from type 'std::__cxx11::basic_string<char>::size_type (std::__cxx11::basic_string<char>::)() const noexcept' {aka 'long unsigned int (std::__cxx11::basic_string<char>::)() const noexcept'} to type 'int'
    6 |   int a=O.size,b=E.size;
      |           ^~~~
a.cc:6:20: error: cannot convert 'std::__cxx11::basic_string<char>::size' from type 'std::__cxx11::basic_string<char>::size_type (std::__cxx11::basic_string<char>::)() const noexcept' {aka 'long unsigned int (std::__cxx11::basic_string<char>::)() const noexcept'} to type 'int'
    6 |   int a=O.size,b=E.size;
      |                    ^~~~
Language: C++

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

int main(){
    string o, e;
    cin >> o >> e;
    for(int i = 0; i < e.size() && i < o.sizse(); i++){
        cout << o[i] << e[i];
    }
    cout << endl;
    return 0; 
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:42: error: 'std::string' {aka 'class std::__cxx11::basic_string<char>'} has no member named 'sizse'; did you mean 'size'?
    7 |     for(int i = 0; i < e.size() && i < o.sizse(); i++){
      |                                          ^~~~~
      |                                          size
Language: C++

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

int main(){
	int a;
    string O,E;
    cin >> O >> E;
      for(int i=0;i<O.size();++i){ 
        cout << O.at(i);
      if(i<E.size()){
        cout << O.at(i));
    }
      }
    cout<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:24: error: expected ';' before ')' token
   11 |         cout << O.at(i));
      |                        ^
      |                        ;
Language: C++

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

int main(){
	int a;
    string O,E;
    cin >> O >> E;
      for(int i=0;i<O.size();++i){ 
        cout << O.at(i);
      }
      if(i<E.size()){
        cout << O.at(i));
    }
    cout<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:10: error: 'i' was not declared in this scope
   11 |       if(i<E.size()){
      |          ^
Language: C++

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

int main(){
  	int j;
    string O,E;
    cin >> O >> E;
      for(int i=0;i<O.size();++i){
       if(E.size(i)<E.size()){ 
        cout << O.at(i);
        cout << E.at(i);
      }
        else{
          cout <<O.at(i);
    }
    }
    cout<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:17: error: no matching function for call to 'std::__cxx11::basic_string<char>::size(int&)'
    9 |        if(E.size(i)<E.size()){
      |           ~~~~~~^~~
In file included from /usr/include/c++/14/string:54,
                 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/basic_string.h:1076:7: note: candidate: '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]'
 1076 |       size() const _GLIBCXX_NOEXCEPT
      |       ^~~~
/usr/include/c++/14/bits/basic_string.h:1076:7: note:   candidate expects 0 arguments, 1 provided
Language: C++

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

int main(){
  	int j;
    string O,E;
    cin >> O >> E;
      for(int i=0;i<O.size();++i){
       if(E.size(i)<=E.size()){ 
        cout << O.at(i);
        cout << E.at(i);
      }
        else{
          cout <<O.at(i);
    }
    }
    cout<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:17: error: no matching function for call to 'std::__cxx11::basic_string<char>::size(int&)'
    9 |        if(E.size(i)<=E.size()){
      |           ~~~~~~^~~
In file included from /usr/include/c++/14/string:54,
                 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/basic_string.h:1076:7: note: candidate: '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]'
 1076 |       size() const _GLIBCXX_NOEXCEPT
      |       ^~~~
/usr/include/c++/14/bits/basic_string.h:1076:7: note:   candidate expects 0 arguments, 1 provided
Language: C++

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

int main(){
  	int j;
    string O,S;
    cin >> O >> S;
	if(O==S){
      for(int i=0;i<O.size();++i){
        cout << O.at(i);
        cout << S.at(i);
      }
    }
  	else{
      for(int i=0;i=<O.size();++i){
        cout << O.at(i);
        cout << S.at(i);
       j=i;
      }
      cout << O.at(j+1);
    }
    cout<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:21: error: expected primary-expression before '<' token
   15 |       for(int i=0;i=<O.size();++i){
      |                     ^