#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;

vector<int> z_function(string s) {
    int n = (int) s.length();
    vector<int> z(n);
    for (int i = 1, l = 0, r = 0; i < n; ++i) {
        if (i <= r)
            z[i] = min (r - i + 1, z[i - l]);
        while (i + z[i] < n && s[z[i]] == s[i + z[i]])
            ++z[i];
        if (i + z[i] - 1 > r)
            l = i, r = i + z[i] - 1;
    }
    return z;
}

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");
    auto rs = s;
    reverse(rs.begin(), rs.end());
    rs += s;
    auto z = z_function(rs);
    int res = rs.size();
    for (int i = n; i < (int)rs.size(); ++i) {
        if (i + z[i] == 2 * n)
            res = min(res, n - z[i]);
    }
    cout << res << endl;
    return 0;
}