criyle/codenet-compile-errors huggingface dataset:
Language: Java

import java.util.*;

public class Main{
  public static void main(String[]args){
    Scanner sc=new Scanner(System.in);
    String S=sc.nextLine();
    
    String[]sr=S.split("");
    
    int count =0;
    
    if(S.length!=1){
      for(int i=0;i<S.length/2;i++){
        if(sr[i]==sr[S.length-i]){
          count+=0;
        }else if(sr[i]!=sr[S.length-i]){
          count+=1;
          sr[i]=sr[S.length-i];
        }
      }
          if(S.length=1){
      System.out.println("0");
    }
    if(count!=0){
      System.out.println("count");
    }

    }
  }

          
          

Compiler output:
Main.java:29: error: reached end of file while parsing
  }
   ^
1 error
Language: C

#include <stdio.h>
 
int main()
{
	int i,a;
 
	char b;
	scanf("%s", &b);
  
    for(i=0; b[a]!='\0'; ++a);

	for ( i = 0; i < a; i++) {
		if (b[ i] != b[a-i+1]) 
        {
          printf("&d",&i)
    }
		

	return 0;
 
}

Compiler output:
main.c: In function 'main':
main.c:10:15: error: subscripted value is neither array nor pointer nor vector
   10 |     for(i=0; b[a]!='\0'; ++a);
      |               ^
main.c:13:22: error: subscripted value is neither array nor pointer nor vector
   13 |                 if (b[ i] != b[a-i+1])
      |                      ^
main.c:13:31: error: subscripted value is neither array nor pointer nor vector
   13 |                 if (b[ i] != b[a-i+1])
      |                               ^
main.c:15:26: error: expected ';' before '}' token
   15 |           printf("&d",&i)
      |                          ^
      |                          ;
   16 |     }
      |     ~                     
main.c:21:1: error: expected declaration or statement at end of input
   21 | }
      | ^
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length();i++){
        int n = 0;
        int m = s.length() - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }
        n++;
        m--;
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}


Compiler output:
Main.java:21: error: ';' expected
      System.out.println(count)
                               ^
1 error
Language: C++

#include <bits/stdv++.h>
using namespace std;
int main()
  {
  char str[1000] ={};
  cin >> str;
  char sta[1000]={};
  int n= strlen(str);
  int j = 0;
  int c=0;
  for(int i = n-1; i >= 0; i--)
    {
    if(str[i]!=str[j]
       {
         c++;
         str[i]=str[j];
         }
    j++;
    }
        cout<<c<<endl;
  return 0;
  }

Compiler output:
a.cc:1:10: fatal error: bits/stdv++.h: No such file or directory
    1 | #include <bits/stdv++.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.
Language: C++

#include <bits/stdc++>
#include <string>
using namespace std;
int main(){
	string S;
  	cin >> S;
	cout << S.size()/2 << endl;
  	return 0;
}


Compiler output:
a.cc:1:10: fatal error: bits/stdc++: No such file or directory
    1 | #include <bits/stdc++>
      |          ^~~~~~~~~~~~~
compilation terminated.
Language: C++

#inslude <bits/stdc++>
#include <string>
using namespace std;
int main(){
	string S;
  	cin >> S;
	cout << S.size()/2 << endl;
  	return 0;
}

Compiler output:
a.cc:1:2: error: invalid preprocessing directive #inslude; did you mean #include?
    1 | #inslude <bits/stdc++>
      |  ^~~~~~~
      |  include
a.cc: In function 'int main()':
a.cc:6:9: error: 'cin' was not declared in this scope
    6 |         cin >> S;
      |         ^~~
a.cc:3:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    2 | #include <string>
  +++ |+#include <iostream>
    3 | using namespace std;
a.cc:7:9: error: 'cout' was not declared in this scope
    7 |         cout << S.size()/2 << endl;
      |         ^~~~
a.cc:7:9: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:7:31: error: 'endl' was not declared in this scope
    7 |         cout << S.size()/2 << endl;
      |                               ^~~~
a.cc:3:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
    2 | #include <string>
  +++ |+#include <ostream>
    3 | using namespace std;
Language: C++

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

// Recursive function to find
// minimum number of insertions
int findMinInsertions(char str[], int l, int h)
{
    // Base Cases
    if (l > h) return INT_MAX;
    if (l == h) return 0;
    if (l == h - 1) return (str[l] == str[h])? 0 : 1;

    // Check if the first and last characters are
    // same. On the basis of the comparison result,
    // decide which subrpoblem(s) to call
    return (str[l] == str[h])?
                    findMinInsertions(str, l + 1, h - 1):
                    (min(findMinInsertions(str, l, h - 1),
                    findMinInsertions(str, l + 1, h)) + 1);
}

// Driver code
int main()
{
    char str[101];
    gets(str);
    cout << findMinInsertions(str, 0, strlen(str) - 1)<<endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
   27 |     gets(str);
      |     ^~~~
      |     getw
Language: C++

#inslude <bits/stdc++>
#include <string>
using namespace std;
int main(){
	string S;
  	cin >> S;
	cout << S.size()/2 << endl;
  	
}

Compiler output:
a.cc:1:2: error: invalid preprocessing directive #inslude; did you mean #include?
    1 | #inslude <bits/stdc++>
      |  ^~~~~~~
      |  include
a.cc: In function 'int main()':
a.cc:6:9: error: 'cin' was not declared in this scope
    6 |         cin >> S;
      |         ^~~
a.cc:3:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    2 | #include <string>
  +++ |+#include <iostream>
    3 | using namespace std;
a.cc:7:9: error: 'cout' was not declared in this scope
    7 |         cout << S.size()/2 << endl;
      |         ^~~~
a.cc:7:9: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:7:31: error: 'endl' was not declared in this scope
    7 |         cout << S.size()/2 << endl;
      |                               ^~~~
a.cc:3:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
    2 | #include <string>
  +++ |+#include <ostream>
    3 | using namespace std;
Language: C++

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

int main(){
    string str;
    cin >> str;
    int count = 0;
    for (size_t i = 0; i < str.length() / 2; i++)
    {
        if (str.at(i) != str.at(str.length - i))
        {
            count++;
        }
        
    }
    cout << count << endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:37: 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 '()' ?)
   11 |         if (str.at(i) != str.at(str.length - i))
      |                                 ~~~~^~~~~~
      |                                           ()
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }
        n++;
        m--;
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}


Compiler output:
Main.java:21: error: ';' expected
      System.out.println(count)
                               ^
1 error
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }
        n++;
        m--;
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}

Compiler output:
Main.java:21: error: ';' expected
      System.out.println(count)
                               ^
1 error
Language: C++

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

// Recursive function to find
// minimum number of insertions
int findMinInsertions(char str[], int l, int h)
{
    // Base Cases
    if (l > h) return INT_MAX;
    if (l == h) return 0;
    if (l == h - 1) return (str[l] == str[h])? 0 : 1;

    // Check if the first and last characters are
    // same. On the basis of the comparison result,
    // decide which subrpoblem(s) to call
    return (str[l] == str[h])?
                    findMinInsertions(str, l + 1, h - 1):
                    (min(findMinInsertions(str, l, h - 1),
                    findMinInsertions(str, l + 1, h)) + 1);
}

// Driver code
int main()
{
    char str[101];
    gets(str);
    cout << findMinInsertions(str, 0, strlen(str) - 1)<<endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
   27 |     gets(str);
      |     ^~~~
      |     getw
Language: C++

#include <stdio.h>


int main(void)
{
    char str[101];
    gets(str);

    int len = 0;
    while(str[len]) len++;

    int cnt = 0;
    for (int i=0; i < len; i++){
        if (i == len - i -1) ;
        else if (str[i] != str[len-i-1]) cnt++;
    }

    printf("%d\n", cnt/2);



    return 0;
} 



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(str);
      |     ^~~~
      |     getw
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
          n++;
          m--;
        }else{
          n++;
          m--;
        }
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}


Compiler output:
Main.java:24: error: ';' expected
      System.out.println(count)
                               ^
1 error
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }else{
          ;
        }
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }else{
          ;
        }
        n++;
        m--;
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}


Compiler output:
Main.java:21: error: ';' expected
      System.out.println(count)
                               ^
Main.java:27: error: class, interface, enum, or record expected
import java.util.Scanner;
^
Main.java:49: error: ';' expected
      System.out.println(count)
                               ^
3 errors
Language: C

#include <stdio.h>

int main(void)
{
    char s[100];
    scanf("%s", s);
    int i;
    
    for(i=0; moji[i]!='\0'; ++i);

    int p,q,count;
    
    q=i;
    count = 0;
    
    for(p=0; p = q; p++,q--){
        if(s[p]==s[q]){
            count++;
        }
    }
    
    printf("%d",count):
    return 0;
}

Compiler output:
main.c: In function 'main':
main.c:9:14: error: 'moji' undeclared (first use in this function)
    9 |     for(i=0; moji[i]!='\0'; ++i);
      |              ^~~~
main.c:9:14: note: each undeclared identifier is reported only once for each function it appears in
main.c:22:23: error: expected ';' before ':' token
   22 |     printf("%d",count):
      |                       ^
      |                       ;
Language: Java

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
     
      int count = 0;
      
      String s = sc.next();
      
      for(int i = 0; i < s.length;i++){
        int n = 0;
        int m = s.length - 1;
        if(s.charAt(n) != s.charAt(m)){
          count++;
        }else{
          ;
        }
      }
      
      System.out.println(count)
      
      
      sc.close();
    }
}

Compiler output:
Main.java:21: error: ';' expected
      System.out.println(count)
                               ^
1 error
Language: C++

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

int main() {
	string s;
	cin >> s;
	int n = s.length();
	for (int i = 0;i < n;++i) {
		int ans = 0;
		if (s[i] != s[n - 1 - i]) {
			++ans;
		}
	}
	cout << ans << endl;
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:15:17: error: 'ans' was not declared in this scope; did you mean 'abs'?
   15 |         cout << ans << endl;
      |                 ^~~
      |                 abs
Language: C++

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

int main(){
  char s[110];
  int cnt=0;
  cin>>s;
  int s_size=strsize(s);
  int ss=s_size/2;
  for(int i=0;i<ss;i++){
    if(s[i]!=s[s_size-i])cnt++;
  }
  cout<<cnt<<endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:14: error: 'strsize' was not declared in this scope; did you mean 's_size'?
    9 |   int s_size=strsize(s);
      |              ^~~~~~~
      |              s_size
Language: C++

#include<iostream>
 
int main(void){
	int i = 0;
 	string s;
	cin >> s;
  
  int N = s.size();
  int half = N / 2;
  int j = half - 1;
  while (j >= 0){
      if (s[j] != s[N-j-1]) i++;
      j--;
  }
  
    printf("%d",i);
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:9: error: 'string' was not declared in this scope
    5 |         string s;
      |         ^~~~~~
a.cc:5:9: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:6:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |         cin >> s;
      |         ^~~
      |         std::cin
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:6:16: error: 's' was not declared in this scope
    6 |         cin >> s;
      |                ^
Language: C++

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


// Recursive function to find
// minimum number of insertions
int findMinInsertions(char str[], int l, int h)
{
    // Base Cases
    if (l > h) return INT_MAX;
    if (l == h) return 0;
    if (l == h - 1) return (str[l] == str[h])? 0 : 1;

    // Check if the first and last characters are
    // same. On the basis of the comparison result,
    // decide which subrpoblem(s) to call
    return (str[l] == str[h])?
                    findMinInsertions(str, l + 1, h - 1):
                    (min(findMinInsertions(str, l, h - 1),
                    findMinInsertions(str, l + 1, h)) + 1);
}

// Driver code
int main()
{
    char str[101];
    gets(str);
    cout << findMinInsertions(str, 0, strlen(str) - 1)<<endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
   27 |     gets(str);
      |     ^~~~
      |     getw
Language: C++

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


// Recursive function to find
// minimum number of insertions
int findMinInsertions(char str[], int l, int h)
{
    // Base Cases
    if (l > h) return INT_MAX;
    if (l == h) return 0;
    if (l == h - 1) return (str[l] == str[h])? 0 : 1;

    // Check if the first and last characters are
    // same. On the basis of the comparison result,
    // decide which subrpoblem(s) to call
    return (str[l] == str[h])?
                    findMinInsertions(str, l + 1, h - 1):
                    (min(findMinInsertions(str, l, h - 1),
                    findMinInsertions(str, l + 1, h)) + 1);
}

// Driver code
int main()
{
    char str[101];
    gets(str);
    cout << findMinInsertions(str, 0, strlen(str) - 1);
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
   27 |     gets(str);
      |     ^~~~
      |     getw
Language: C++

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

using namespace std;

int main() {
	string str;

	cin >> str;

	// 長さを取得
	size_t size = str.length();

	string front = str.substr(0, size / 2);
	string back = str.substr(size / 2);
	string revBack = reverse(back);

	int cnt = 0;
	for (int i = 0; i < size / 2; ++i){
		if (front[i] != revBack[i]) {
			cnt++;
		}
	}

	printf("%i\n", cnt);

	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:17:26: error: 'reverse' was not declared in this scope
   17 |         string revBack = reverse(back);
      |                          ^~~~~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
	char a[101];
	int l,i,j,s=0;
	gets(a);
	l=strlen(a);
	//cout<<l<<endl;
	for(i=l-1,j=0;i>=l/2&&i>=j;i--,j++){
		//cout<<i<<" "<<j<<endl;
		if(int(a[i])!=int(a[j])) s++;
	}
	cout<<s;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:9: error: 'gets' was not declared in this scope; did you mean 'getw'?
    6 |         gets(a);
      |         ^~~~
      |         getw
Language: C++

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


int main(void)
{
    char str[123];
    gets(str);

    int len = 0;
    while(str[len]) len++;

    int cnt = 0;
    for (int i=0; i < len; i++){
        if (i == len - i -1) ;
        else if (str[i] != str[len-i-1]) cnt++;
    }

    printf("%d\n", cnt/2);



    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(str);
      |     ^~~~
      |     getw
Language: C++

#include <bits/stdc++.h> 
using namespace std; 
   
  
// Returns length of LCS for X[0..m-1], Y[0..n-1].  
int lcs( string X, string Y, int m, int n )  
{  
    int L[n+1][n+1];  
    int i, j;  
      
    /* Following steps build L[m+1][n+1] in bottom  
        up fashion. Note that L[i][j] contains length  
        of LCS of X[0..i-1] and Y[0..j-1] */
    for (i = 0; i <= m; i++)  
    {  
        for (j = 0; j <= n; j++)  
        {  
        if (i == 0 || j == 0)  
            L[i][j] = 0;  
      
        else if (X[i - 1] == Y[j - 1])  
            L[i][j] = L[i - 1][j - 1] + 1;  
      
        else
            L[i][j] = max(L[i - 1][j], L[i][j - 1]);  
        }  
    }  
      
    /* L[m][n] contains length of LCS for X[0..n-1]  
        and Y[0..m-1] */
    return L[m][n];  
}  
  
void reverseStr(string& str)  
{  
    int n = str.length();  
  
    // Swap character starting from two  
    // corners  
    for (int i = 0; i < n / 2; i++)  
        swap(str[i], str[n - i - 1]);  
}  
  
// LCS based function to find minimum number of  
// insertions  
int findMinInsertionsLCS(string str, int n)  
{  
    // Creata another string to store reverse of 'str'  
    string rev = "";  
    rev = str;  
    reverseStr(rev);  
      
    // The output is length of string minus length of lcs of  
    // str and it reverse  
    return (n - lcs(str, rev, n, n));  
}  
  
// Driver code 
int main()  
{  
    string str;
  cin>>s;
    cout << findMinInsertionsLCS(str, str.length());  
    return 0;  
}  

Compiler output:
a.cc: In function 'int main()':
a.cc:62:8: error: 's' was not declared in this scope
   62 |   cin>>s;
      |        ^
Language: C

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

int main()
{
	char str[101];
	scnaf("%s", str);
	int length = strlen(str);
	int count = 0;
	
	for(int i = 0; i < length / 2; i++){
		if(str[i] != str[length]){
			count++;
		}
	}
	printf("%d\n", count);
	
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:7:9: error: implicit declaration of function 'scnaf'; did you mean 'scanf'? [-Wimplicit-function-declaration]
    7 |         scnaf("%s", str);
      |         ^~~~~
      |         scanf
Language: Java

import java.util.Scanner;
class Main{
	public static void main(String[] aegs){
    	Scanner sc = new Scanner(System.in);
      	String s = sc.next();
      	int count = 0;
      	int i =	0;
      	int j = s.length() - 1;
      	for(;i<j;){
        	if(s.charAt(i) != s.charAt(j)){
            	count++;
            i++;
            j--;
        }
      	sc.close();
    }
}

Compiler output:
Main.java:17: error: reached end of file while parsing
}
 ^
1 error
Language: Java

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		int Count = 0;
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		int length = str.length();
		if(length%2 == 0) {
			for(int i = 0; i <= length/2-1; i++) {
				if(str.charAt(i) != str.charAt(length-1-i)) {
					Count++;
				}
			}
		}else {
			for(int i = 0; i <= (length-1)/2-1; i++) {
				if(str.charAt(i) != str.charAt(length-1-i)) {
					Count++;
				}
			}
		}
		System.out.println(Count);
	}

Compiler output:
Main.java:22: error: reached end of file while parsing
	}
	 ^
1 error
Language: C++

#include <stdio.h>
#include <math.h>
#include <string>
#include <float.h>
#include <iostream>
#include <map>
#include <vector>
using namespace std;

int main()
{
	char szS[100];

	cin >> szS;
	int nLen = strlen(szS);
	int nLpMax = 0;
	if(0 == nLen%2)
		nLpMax = nLen / 2;
	else
		nLpMax = nLen / 2;
	int nHag = 0;
	for (int i = 0; i < nLpMax; i++)
	{
		int nRvsIdx = nLen - 1 - i;
		if (szS[i] != szS[nRvsIdx])
			nHag++;
	}
	cout << nHag;
	return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:15:20: error: 'strlen' was not declared in this scope
   15 |         int nLen = strlen(szS);
      |                    ^~~~~~
a.cc:8:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    7 | #include <vector>
  +++ |+#include <cstring>
    8 | using namespace std;
Language: C++

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

int main(){
    string S;
    cin >> S;
    int a = S.size();
    int b = a - 1;
    int c = 0;
    for(int i = 0;i < (b / 2);i++){
        if(S.at(i) != S.at(b - i){
            c = c + 1;
        }
    }
    cout << c << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:34: error: expected ')' before '{' token
   11 |         if(S.at(i) != S.at(b - i){
      |           ~                      ^
      |                                  )
a.cc:14:5: error: expected primary-expression before '}' token
   14 |     }
      |     ^
Language: C++

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

int main(){
    string S;
    cin >> S;
    int a = S.size();
    int b = a - 1;
    int c = 0;
    for(int i = 0;i < (b / 2);i++){
        if(S.at(i) != S.st(b - i){
            c = c + 1;
        }
    }
    cout << c << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:25: error: 'std::string' {aka 'class std::__cxx11::basic_string<char>'} has no member named 'st'; did you mean 'at'?
   11 |         if(S.at(i) != S.st(b - i){
      |                         ^~
      |                         at
a.cc:11:34: error: expected ')' before '{' token
   11 |         if(S.at(i) != S.st(b - i){
      |           ~                      ^
      |                                  )
a.cc:14:5: error: expected primary-expression before '}' token
   14 |     }
      |     ^
Language: C++

#include <iostream>
using namespace std;
    
int main(){
  string s;
  cin >> s;
  int ans = 0;
  for(int i=0;i<s.length()/2-1;++i){
  	if(s[i]!=s[n-1-i])
      	ans++;
  }
  if(s.length()%2==0 && n>=2){
  	ans += (s[n/2]!=s[n/2+1]);
  }
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:20: error: 'n' was not declared in this scope
    9 |         if(s[i]!=s[n-1-i])
      |                    ^
a.cc:12:25: error: 'n' was not declared in this scope
   12 |   if(s.length()%2==0 && n>=2){
      |                         ^
Language: C++

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

}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:10: error: request for member 'at' in 'n', which is of non-class type 'int'
   10 |     if(n.at[i] == n.at[n.size()-i]{
      |          ^~
a.cc:10:21: error: request for member 'at' in 'n', which is of non-class type 'int'
   10 |     if(n.at[i] == n.at[n.size()-i]{
      |                     ^~
a.cc:10:26: error: request for member 'size' in 'n', which is of non-class type 'int'
   10 |     if(n.at[i] == n.at[n.size()-i]{
      |                          ^~~~
a.cc:10:35: error: expected ')' before '{' token
   10 |     if(n.at[i] == n.at[n.size()-i]{
      |       ~                           ^
      |                                   )
a.cc:15:8: error: expected primary-expression before '}' token
   15 |        }
      |        ^
a.cc: At global scope:
a.cc:19:1: error: expected declaration before '}' token
   19 | }
      | ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
char s[128];
int main()
{
    int i,cnt=0;
    gets(s);
    int l=strlen(s);
    for(i=0;i<l;i++)
    {
    	if(s[i]!=s[l-1-i])
    		cnt++;
	}
	cout<<cnt/2;
    return 0;
}

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(s);
      |     ^~~~
      |     getw
Language: C

#include<stdio.h>
#define N 100

int main(){

	int m;
	int Ans=0;

	char S[N];
	scanf("%s",&S);
	for(m=0; S[m]!='\0'; ++m);

	for(int i = 0; i = m/2 ;i++){
		if(S[i] != S[m - i]){
			S[m - i] = S[i];
			Ans++
		}
	}

	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:16:30: error: expected ';' before '}' token
   16 |                         Ans++
      |                              ^
      |                              ;
   17 |                 }
      |                 ~
Language: C++

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

typedef long long ll;
typedef unsigned short int unsi;
typedef unsigned int uni;
typedef unsigned long int unli;

using namespace std;

int main(){
	string S;
	cin >> S;
	
	int l = S.length();
	int Count = 0;
	
	if (l % 2 == 0) {
		for (int i = 0; i < l / 2; i++) {
			if (S[i] != S[l - 1 - i]) {
				Count++;
			}
		}
	} else {
		for (int i = 0; i < (l - 1) / 2; i++) {
			if (S[i] != S[l - 1 - i]) {
				Count++;
			}
		}
	}

	cout << Count << endl;


Compiler output:
a.cc: In function 'int main()':
a.cc:35:31: error: expected '}' at end of input
   35 |         cout << Count << endl;
      |                               ^
a.cc:14:11: note: to match this '{'
   14 | int main(){
      |           ^
Language: C++

#include<fstream>
#include<string>
#include<iostream>
#include<sstream>
#include<iterator>
#include<cmath>
#include<stdio.h>

using namespace std;

int main(){
string txt;
 cin >> txt;
 int N = txt.length();
  int n = N/2;
  int i;
  char c;
  char d;
  int t = 0;
  for(i=0;i<n;i++){
   c = txt[i];
   d = txt[N-1-i]
   if(c!=d)t++;}
  cout << t << endl; 
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:22:18: error: expected ';' before 'if'
   22 |    d = txt[N-1-i]
      |                  ^
      |                  ;
   23 |    if(c!=d)t++;}
      |    ~~
Language: C

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


int main(){
  char s;
  scanf("%s",s);
  int i,j
  int x=0;
  for(n=0; moji[n]!='\0'; ++n);
  for(i=0,j=n/2;i<n/2,j<n;i++,j++){
     if(s[i]!=s[j]){
       ++x;}
  }
  printf("%d",x);
  return 0;
}

Compiler output:
main.c: In function 'main':
main.c:9:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'int'
    9 |   int x=0;
      |   ^~~
main.c:10:7: error: 'n' undeclared (first use in this function)
   10 |   for(n=0; moji[n]!='\0'; ++n);
      |       ^
main.c:10:7: note: each undeclared identifier is reported only once for each function it appears in
main.c:10:12: error: 'moji' undeclared (first use in this function)
   10 |   for(n=0; moji[n]!='\0'; ++n);
      |            ^~~~
main.c:11:11: error: 'j' undeclared (first use in this function)
   11 |   for(i=0,j=n/2;i<n/2,j<n;i++,j++){
      |           ^
main.c:12:10: error: subscripted value is neither array nor pointer nor vector
   12 |      if(s[i]!=s[j]){
      |          ^
main.c:13:10: error: 'x' undeclared (first use in this function)
   13 |        ++x;}
      |          ^
Language: C++

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

typedef long long ll;
typedef unsigned short int unsi;
typedef unsigned int uni;
typedef unsigned long int unli;

using namespace std;

int main(){
	string S;
	cin >> S;
	
	int l = S.length;
	int Count = 0;
	
	if (l % 2 == 0) {
		for (int i = 0; i < l / 2; i++) {
			if (S[i] != S[l - 1 - i]) {
				Count++;
			}
		}
	} else {
		for (int i = 0; i < (l - 1) / 2; i++) {
			if (S[i] != S[l - 1 - i]) {
				Count++;
			}
		}
	}

	cout << Count << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:18:19: error: cannot convert 'std::__cxx11::basic_string<char>::length' 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'
   18 |         int l = S.length;
      |                   ^~~~~~
Language: C++

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

int isP(char str[]) 
{ 
  	int count=0;
    int l = 0; 
    int h = strlen(str) - 1; 
    while (h > l) { 
        if (str[l++] != str[h--]) count++;
    } 
  return count;
} 
int main(){
  char s[];
  cin>>s;
  int ans = isP(s);
  cout<<ans<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:8: error: storage size of 's' isn't known
   15 |   char s[];
      |        ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
  string S;
  int count;
  cin>>S;
  for(int i=0;i<S.size()/2;i++){if(S.at(i)!=S.at(S.size()-i)count++;)}
  cout<<count<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:61: error: expected ';' before 'count'
    8 |   for(int i=0;i<S.size()/2;i++){if(S.at(i)!=S.at(S.size()-i)count++;)}
      |                                                             ^~~~~
      |                                                             ;
a.cc:8:69: error: expected primary-expression before ')' token
    8 |   for(int i=0;i<S.size()/2;i++){if(S.at(i)!=S.at(S.size()-i)count++;)}
      |                                                                     ^
a.cc:8:70: error: expected primary-expression before '}' token
    8 |   for(int i=0;i<S.size()/2;i++){if(S.at(i)!=S.at(S.size()-i)count++;)}
      |                                                                      ^
Language: C++

#include <bits/stdc++.h>
#define N 1000005
#define ll long long int 	
#define MP make_pair
#define pb push_back
#define ppb pop_back
#define sp " "
#define endl "\n"
#define fi first
#define se second
#define ii pair<int,int>
#define lli pair<ll,ll>
#define fast cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(false)
#define fast2 freopen ("badhair.gir","r",stdin);freopen ("badhair.cik","w",stdout);
#define mod 1000000007
#define fs(x,y) for(ll i=1;i<=y;i++) cin>>x[i]
#define fo(i,x,y) for(ll i=x;i<=y;i++)
#define INF 1000000000005
using namespace std;

ll n,m,ar[N],sum,t;



int main()
{
	fast;
	cin>>s+1;
	n=strlen(s+1);
	fo(i,1,n/2)
		if(s[i]!=s[n-i+1])
			sum++;
		cout<<sum;

}



/*     cd onedrive\desktop\kod
cls

Sinav:21-22 aralik
Aciklama: Muhtemelen 25 aralik
*/

Compiler output:
a.cc: In function 'int main()':
a.cc:28:14: error: 's' was not declared in this scope
   28 |         cin>>s+1;
      |              ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main()
{
    char a[1005];
    gets(a);
    int l=0,r=strlen(a)-1;
    int ans=0;
    while(l<r)
    {
        if(a[l]!=a[r])
            ans++;
        l++;
        r--;
    }
    printf("%d\n",ans);
    return 0;
}


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
Language: C++

#include<iostream>
#include<string>
using namespace std;
int main(){
  string s;
  cin>>s;
  int ans=0;
  for(int i=0;i<size.(s);i++){
    if(s[i]!=s[size(s)-i]) ans++;
  }
  cout<<ans<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:22: error: expected unqualified-id before '(' token
    8 |   for(int i=0;i<size.(s);i++){
      |                      ^
Language: C++

#include<stdio.h>
#include<string.h>
int main()
{
	int l,i,a=0;
	char s[105];
	scanf("%s",s);
	l=strlen(s);
	for(i=0;i<(l+1)/2;i++)
	{
		if(s[i]!=s[l-1-i])a++;
	}
	iprintf("%d\n",a);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:9: error: 'iprintf' was not declared in this scope; did you mean 'vprintf'?
   13 |         iprintf("%d\n",a);
      |         ^~~~~~~
      |         vprintf
Language: C++

#include <iostream>
using namespace std;
typedef long long ll;

int main() {
  string s, c;
  cin >> s;
  c = s;
  reverse(c.begin(), c.end());
  int cnt;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] != c[i]) cnt++;
  }

  cout << cnt / 2 << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:3: error: 'reverse' was not declared in this scope
    9 |   reverse(c.begin(), c.end());
      |   ^~~~~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
  ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
  
    string str;
  	
  cin>>str;
  
  int cnt=0;
  
  for(int i=0;i<str.size()/2;i++)
  {
    if(str[i]!=str[str.size()-i-1])
      cnt++;
  }
  
  cout<<cnt<<endl;
  
  
  
  
    
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:53: error: expected ';' before 'string'
    5 |   ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
      |                                                     ^
      |                                                     ;
    6 | 
    7 |     string str;
      |     ~~~~~~                                           
a.cc:9:8: error: 'str' was not declared in this scope; did you mean 'std'?
    9 |   cin>>str;
      |        ^~~
      |        std
Language: C++

#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>

#define REP(i,n) for(int i = 0; i < n; i++)
#define ll long long
#define PI 3.141592653589

using namespace std;

int main(void){
    char s[110]; cin >> s;
    int n = strlen(s), ctr = 0;

    REP(i,n/2){
        if(s[i] != s[n-i-1]) ctr++;
    }
    cout << ctr;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:14:13: error: 'strlen' was not declared in this scope
   14 |     int n = strlen(s), ctr = 0;
      |             ^~~~~~
a.cc:5:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    4 | #include <cstdio>
  +++ |+#include <cstring>
    5 | 
a.cc:17:30: error: 'ctr' was not declared in this scope
   17 |         if(s[i] != s[n-i-1]) ctr++;
      |                              ^~~
a.cc:19:13: error: 'ctr' was not declared in this scope
   19 |     cout << ctr;
      |             ^~~
Language: C++

#include <iostream>
#include<iomanip>
#include <map>
#include <algorithm>
#include <vector>
#include <string>
#include <utility>
#include <queue>
#define INF 1e9+7
#define rep(i,n) for(ll i=0;i<n;i++)
#define NO cout<<"NO"<<endl;
#define YES cout<< "YES"<<endl;
#define No cout<< "No"<<endl;
#define Yes cout<< "Yes"<<endl;
#define all(a) a.begin(),a.end()
#define P pair<int,int>
#define space ' '
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

//(int)'a'は97 (int)'A'は65 (int)'1'は49
//おまじない

const int maxn = 1000000;

　int main(){
    
    string s;
    cin >> s;
    int r,l;
    int n=(int)s.size();
    int ans = 0;
    
    if(n%2==0){
        r = n/2;
        l = n/2-1;
    }else{
        r = n/2+1;
        l = n/2-1;
    }
    
    for(;r<n;r++){
        if(s[r]!=s[l])ans++;
        l--;
    }
    
    cout << ans<<endl;
    
    return 0;
}


Compiler output:
a.cc:27:1: error: extended character 　 is not valid in an identifier
   27 | 　int main(){
      | ^
a.cc:27:1: error: '\U00003000int' does not name a type
   27 | 　int main(){
      | ^~~~~
Language: C++

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

int main()
{
  string s;
  cin >> s;
  int cnt=0;
  
  for(int i =0 ;i < s.size()/2;i ++)
    if(s[i]!= s[n-1-i])
      	cnt++;
  cout<< cnt;
	
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:17: error: 'n' was not declared in this scope
   11 |     if(s[i]!= s[n-1-i])
      |                 ^
Language: C++

#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define E "\n"

using namespace std;
const long long MOD = (long long)1e9 + 7;

int len;
string s;

int main()
{
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> s;
    len = s.length();
    int cnt = 0;
    for (int i = 0; i < len/2; i++) {
        if (s[i] != s[n - 1 - i]) cnt++;
    }
    cout << cnt << E;
    //system("pause");
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:23: error: 'n' was not declared in this scope
   21 |         if (s[i] != s[n - 1 - i]) cnt++;
      |                       ^
Language: C++

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <utility>

typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
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;
}

using namespace std;

int main() {
    string S, T;
    cin >> S;
    T = S;
    int cnt = 0;
    reverse(begin(T), end(T));
    for (int i = 0; i< (int)S.size(); i++) {
        if (S[i] != T[i]) cnt++; 
    }
    cout << cnt << endl;
    return 0;
}


Compiler output:
a.cc:13:9: error: 'pair' does not name a type
   13 | typedef pair<ll, ll> l_l;
      |         ^~~~
a.cc:14:9: error: 'pair' does not name a type
   14 | typedef pair<int, int> i_i;
      |         ^~~~
Language: C++

#include <bits/stdc++.h>
#define int long long int
#define ldouble long double
#define vin vector<int> 
#define rep(i,a,n) for(i=(a);i<(n);i++)
#define INF (int)1000000007

//setprecision()<<

using namespace std;

void fin(int i,int n,vin &a){
    rep(i,0,n){
        cin>>a.at(i);
    } 
} 

signed main() {
    int i;
    string s;
    cin>>s;
    int cnt=0;
    for(int i=0;i<s.size()/2;i++){
        if(s.at(i)!=s.at(s.size-1-i)){
            cnt++;
        }

    }
    cout<<cnt<<endl;
return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:24:28: 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 '()' ?)
   24 |         if(s.at(i)!=s.at(s.size-1-i)){
      |                          ~~^~~~
      |                                ()
Language: C++

#include <iostream>
#include <string>
#include <vector>
using namespace std;
using namespace std::literals;

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

  int counter = 0;
  int n = (int)s.size();
  for (int i = 0; i < n / 2; ++i) {
    if (s[i] != s[n - 1 - i])
      counter++;

    cout << counter;

    return 0;
  }


Compiler output:
a.cc: In function 'int main()':
a.cc:20:4: error: expected '}' at end of input
   20 |   }
      |    ^
a.cc:7:12: note: to match this '{'
    7 | int main() {
      |            ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
#define endl '\n'
#define f1 first
#define s2 second
#define pb push_back
#define mp make_pair
#define ll long long
#define fri(a) freopen(a,"r",stdin);
#define fro(a) freopen(a,"w",stdout);
const int N=1e5+4;

int ans;
string str;


int main(){
	//fri("in.txt");
	//fro("out.txt");
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cin>>str;
	for(int i=0;i<str.length();i++){
		if(str[i]!=str[n-i-1])ans++;
	}
	cout<<ans<<endl;
return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:25:32: error: 'n' was not declared in this scope
   25 |                 if(str[i]!=str[n-i-1])ans++;
      |                                ^
Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using static Input;
using NX = System.Int64;


public class Prog
{
    public static void Solve()
    {
        string s = NextString();
        int N = s.Length;
        int ans = 0;
        for (int i = 0; i < N / 2; i++) if (s[i] != s[N - 1 - i]) ans++;
        Console.WriteLine(ans);
    }
    public static void Main()
    {
        var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        Console.SetOut(sw);
        Solve();
        Console.Out.Flush();
        return;
    }
}
public class Input
{
    public const long MOD = 1000000007;
    public const int INF = 1000000007;
    private static Queue<string> q = new Queue<string>();
    private static void Confirm() { if (q.Count == 0) foreach (var s in Console.ReadLine().Split(' ')) q.Enqueue(s); }
    public static int NextInt() { Confirm(); return int.Parse(q.Dequeue()); }
    public static long NextLong() { Confirm(); return long.Parse(q.Dequeue()); }
    public static string NextString() { Confirm(); return q.Dequeue(); }
    public static double NextDouble() { Confirm(); return double.Parse(q.Dequeue()); }
    public static int[] LineInt() { return Console.ReadLine().Split(' ').Select(int.Parse).ToArray(); }
    public static long[] LineLong() { return Console.ReadLine().Split(' ').Select(long.Parse).ToArray(); }
    public static string[] LineString() { return Console.ReadLine().Split(' ').ToArray(); }
    public static double[] LineDouble() { return Console.ReadLine().Split(' ').Select(double.Parse).ToArray(); }
    public long Abs(long a, long b) => Math.Abs(a - b);
}


Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:2:7: error: expected nested-name-specifier before 'System'
    2 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Linq;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'static'
    4 | using static Input;
      |       ^~~~~~
a.cc:5:12: error: 'System' does not name a type
    5 | using NX = System.Int64;
      |            ^~~~~~
a.cc:8:1: error: expected unqualified-id before 'public'
    8 | public class Prog
      | ^~~~~~
a.cc:27:1: error: expected unqualified-id before 'public'
   27 | public class Input
      | ^~~~~~
Language: C++

                          
                                    #include <iostream>
                                    #include <iomanip>
                                    #include <sstream>
                                    #include <cstring>
                                    #include <vector>
                                    #include <deque>
                                    #include <queue>
                                    #include <set>
                                    #include <map>
                                    #include <valarray>
                                    #include <iterator>
                                    #include <functional>
                                    #include <limits>
                                    #include <algorithm>
                                    #include <numeric>
                                    #include <cmath>
                                    #include <cassert>
                                    #include <unordered_map>
                                    #include <unordered_set>
                                    #include <stack>
                                    using namespace std;
                                    #define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
                                     #define trace(x) cerr << #x << ": " << x << " " << endl;
                                 
                                    typedef int64_t ll;
                                 
                                    #define endl '\n'
                                    #define int ll
                                    ll mod=1e9+7;
                                    ll mod1=1e9+5;
                                    
                                    ll power(ll a,ll b)
                                    {
                                        if(b==0) return 1;
                                        else if(b%2==0)
                                            return power((((a%mod)*(a%mod))%mod),b/2)%mod;
                                        else return ((a%mod)*(power((((a%mod)*(a%mod))%mod),b/2)%mod))%mod;
                                    }
                                
                                    
                                int32_t main()
                                {
                                    IOS
                                  
                                string s;
                                cin>>s;
                                int n=s.length();
                                int ans=0;
                                for(int i=0;<n/2;i++)
                                {
                                    if(s[i]!=s[n-i-1])
                                        ans++;
                                }
                                cout<<ans;

                                }                       


Compiler output:
a.cc: In function 'int32_t main()':
a.cc:50:45: error: expected primary-expression before '<' token
   50 |                                 for(int i=0;<n/2;i++)
      |                                             ^