BubbleSecretary

Well the task seem in the first look easy, but I don't know what exactly I'm doing wrong. Maybe I don't understand the task clearly, but here is my code:

# include <iostream>
using namespace std;


char sheet[ 105 ][ 45 ];


int main(){
    
    int n, m, diff, sol = 0, S1;
    scanf("%d %d", &n, &m );

    for(int i=0; i < n; i++ )
        scanf("%s", sheet[i] );
        
    for(int i=0; i < n; i++ ){
    
       for(int j=0; j < n; j++ ){
              
         if( i == j )continue;   
         
         diff = 0;    
         for(int p=0; p < m; p++ ){     
              if( sheet[ i ][ p ] != sheet[ j ][ p ] )diff++;        
              if( diff > 1 )break;
         }
    
          if( diff > 1 )break;
      }
    
      if( diff <= 1 ){ sol++; S1 = i; }
   }
     
    
    if( sol == 1 )printf("%s\n", sheet[S1] );
    else if( sol > 1 )printf("AMBIGUOUS\n"); 
    else printf("IMPOSSIBLE\n"); 
   
    return 0;
}

Very simple brute force.
So can someone tell me what am I doing wrong. thx.

I am not sure for the code but example is wrong. Answer should be the sequence, wright?