#include <bits/stdc++.h>
using namespace std;

constexpr int maxn = 1000 * 1000 + 5;

int r[maxn * 2];
void manacher(const string &s, int n, int * r) {
    for(int i = 0, m = 0, k = 0, p = 0; i < 2 * n - 1; m = i++ - 1) {
        while (p < k and i / 2 + r[m] != k)
            r[i++] = min(r[m--], (k + 1 - p++) / 2);
        while (k + 1 < n and p > 0 and s[k + 1] == s[p - 1])
            k++, p--;
        r[i] = (k + 1 - p++) / 2;
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n; cin >> n;
    string s; cin >> s;

    manacher(s, n, r);
    int res = n;
    for(int i = 0; i < 2 * n - 1; i++) {
        if(i % 2 == 0) {
            int pos = i / 2;
            if(n - pos == r[i] + 1) {
                res = min(res, n - (r[i] * 2 + 1));
            }
        } else {
            int pos = i / 2;
            if(n - pos == r[i] + 1) {
                res = min(res, n - (r[i] * 2));
            }
        }
    }

    cout << res << "\n";
}