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

string reverse(string s) {
    for (int i = 0; i < (int)s.length()/2; ++i) {
        swap(s[i], s[s.length()-1-i]);
    }
    return s;
}

int l[1000000];

int main(){
    int n;
    string s;

    cin >> n >> s;

    s = reverse(s) + "#" + s;
    //cout << s << endl;


    int x = 0;
    l[0] = 0;
    for (int i = 1; i < (int)s.size(); ++i) {
        //cout << s[i] << endl;
        while (x) {
            if (s[i] == s[x]) {
                break;
            }
            else x = l[x-1];
        }
        if (s[i] == s[x]) x++;
        l[i] = x;
    }

    //cout << "xd" << endl;

    int answer = l[s.size()-1];
    /*for (int i = 0; i < (int)s.size(); ++i) {
        answer = max(answer, l[i]);
    }*/

    printf("%d\n", n-answer);
    //cout << s << endl;
    //for (int i = 0; i < s.size(); ++i) cout << l[i];
}