#include <bits/stdc++.h>

using namespace std;

string str, rstr;

int main() {
    int n;
    cin >> n >> str;
    rstr = str;
    reverse(rstr.begin(), rstr.end());
    long long hash = 0, rhash = 0, cur = 1;
    int len = 0;
    for(int i = 0; i < n; i++){
        // normalno, od zadaj
        hash = hash + (str[n - 1 - i] - 'a' + 1) * cur;
        cur *= 37;


        // reverse, od spredaj
        rhash = rhash * 37 + (rstr[i] - 'a' + 1);

        if(rhash == hash){
            len = i + 1;
        }
    }

    printf("%d\n", n - len);
    
    return 0;
}