Language: C++

#include <stdio.h>

int main() {
    int i,a,n,sum=0;
    
//    for(i=1;i<=44720;i++){
//        sum+=i;
//    }
//    printf("%d\n",sum);
//    return 0;
    scanf("%d",&n); 

    for(i=1;i<=n;i++){
        a=sum;
        sum+=i;
        if(n>a && n<=sum){
            printf("%d\n",i);
            return 0;
        }

    }
    
//    sum=n;
//    for(i=1;i<=n;i++){
//
//        if(sum>i)
//            sum-=i;    
//        else{
//            printf("%d\n",i);
//            return 0;
//        }
//    }
    
    
    
}

Compiler output:
a.cc:4:1: error: extended character   is not valid in an identifier
    4 |     int i,a,n,sum=0;
      | ^
a.cc:4:1: error: extended character   is not valid in an identifier
a.cc:4:1: error: extended character   is not valid in an identifier
a.cc:4:1: error: extended character   is not valid in an identifier
a.cc:5:1: error: extended character   is not valid in an identifier
    5 |     
      | ^
a.cc:5:1: error: extended character   is not valid in an identifier
a.cc:5:1: error: extended character   is not valid in an identifier
a.cc:5:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
   11 |     scanf("%d",&n);
      | ^
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:11:1: error: extended character   is not valid in an identifier
a.cc:13:1: error: extended character   is not valid in an identifier
   13 |     for(i=1;i<=n;i++){
      | ^
a.cc:13:1: error: extended character   is not valid in an identifier
a.cc:13:1: error: extended character   is not valid in an identifier
a.cc:13:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
   14 |         a=sum;
      | ^
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:14:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
   15 |         sum+=i;
      | ^
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:15:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
   16 |         if(n>a && n<=sum){
      | ^
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:16:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
   17 |             printf("%d\n",i);
      | ^
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:17:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
   18 |             return 0;
      | ^
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:18:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
   19 |         }
      | ^
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:19:1: error: extended character   is not valid in an identifier
a.cc:21:1: error: extended character   is not valid in an identifier
   21 |     }
      | ^
a.cc:21:1: error: extended character   is not valid in an identifier
a.cc:21:1: error: extended character   is not valid in an identifier
a.cc:21:1: error: extended character   is not valid in an identifier
a.cc:22:1: error: extended character   is not valid in an identifier
   22 |     
      | ^
a.cc:22:1: error: extended character   is not valid in an identifier
a.cc:22:1: error: extended character   is not valid in an identifier
a.cc:22:1: error: extended character   is not valid in an identifier
a.cc:33:1: error: extended character   is not valid in an identifier
   33 |     
      | ^
a.cc:33:1: error: extended character   is not valid in an identifier
a.cc:33:1: error: extended character   is not valid in an identifier
a.cc:33:1: error: extended character   is not valid in an identifier
a.cc:34:1: error: extended character   is not valid in an identifier
   34 |     
      | ^
a.cc:34:1: error: extended character   is not valid in an identifier
a.cc:34:1: error: extended character   is not valid in an identifier
a.cc:34:1: error: extended character   is not valid in an identifier
a.cc:35:1: error: extended character   is not valid in an identifier
   35 |     
      | ^
a.cc:35:1: error: extended character   is not valid in an identifier
a.cc:35:1: error: extended character   is not valid in an identifier
a.cc:35:1: error: extended character   is not valid in an identifier
a.cc: In function 'int main()':
a.cc:4:1: error: '\U000000a0\U000000a0\U000000a0\U000000a0int' was not declared in this scope
    4 |     int i,a,n,sum=0;
      | ^~~~~~~
a.cc:5:1: error: '\U000000a0\U000000a0\U000000a0\U000000a0' was not declared in this scope
    5 |     
      | ^~~~
a.cc:13:9: error: 'i' was not declared in this scope
   13 |     for(i=1;i<=n;i++){
      |         ^
a.cc:13:16: error: 'n' was not declared in this scope
   13 |     for(i=1;i<=n;i++){
      |                ^
a.cc:22:5: error: expected ';' before '\U000000a0\U000000a0\U000000a0\U000000a0'
   22 |     
      |     ^
      |     ;
......
   33 |     
      | ~~~~