I think my code is correct..
what's the tricky input? or what's wrong with my code?
I just made a O(n^2) algorithm to search
here is my code:
#include <stdio.h>
#include <string.h>
char a[1003],b[1003];

int main(){
  int i,j,u,v,l,ind,res=0,tmp;
  scanf("%s",&a);
  l=strlen(a);
  for(i=0;i<l;i++)
    b[i]=a[l-1-i];
  for(i=0;i<l;i++)
    for(j=0;j<l;j++)
      if(a[i]==b[j]){
         tmp=0;
         for(u=i+1,v=j+1;v<l;u++,v++){
            if(a[u]==b[v])
              tmp++;
            else
              break;
         }
         if(tmp>=res){
           res=tmp;
           ind=i;
         }
     }
   for(i=ind;i<=ind+res;i++)
      printf("%c",a[i]);
   printf("\n");
  return 0;
}

AB

your answer: B
correct answer: A