#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;
using ii = pair<int,int>;

const ii N_range = { 1, 4*1e5 };
const int K = 100;
const int MAX_CASE_CNT = 1000;
const int MOD = 1e9+7;

bool isPalindrome(const string & s) {
    for (int i = 0; i < (int)s.size(); ++i)
        if (s[i] != s[s.size()-i-1])
            return false;
    return true;
}

int main() {
    ios::sync_with_stdio(0);
    int    n;
    string s;
    assert(cin >> n && "Could not read N");
    assert(N_range.ff <= n && n <= N_range.ss && "Invalid value of N");
    assert(cin.get() == '\n' && "Something else than new line follows N");
    assert(cin >> s && "Could not read S");
    assert(n == (int)s.size() && "N does not correspond to length of S");
    assert(s.find_first_not_of("abcdefghijklmnopqrstuvwxyz") == string::npos && "S contains faulty characters");
    for (int i = 0; i <= n; ++i) {
        auto tmp = s;
        for (int j = i; j; --j)
            tmp.push_back(s[j-1]);
        // cout << tmp << endl;
        if (isPalindrome(tmp)) {
            cout << i << endl;
            return 0;
        }
    }
    return 0;
}