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

int main(){
    int N;
    string str;
    cin >>N >>str;
    int i=0, j=N-1, length = 0;
    int last =-1;
    while(i<j){
        if(str[i] == str[j]){
            --j;
            ++i;
            if(last == -1){
                last = i;
            }
            length+=2;
        }
        else if(length){
            length=0;
            j=N-1;
            i = last;
            last = -1;
            
        }
        else{
            ++i;
        }
    }
    if(j==i){
        length++;
    }
    cout << N-length<<endl;

    return 0;
}