#include <bits/stdc++.h>

#define MOD 1000000007ll

using namespace std;

typedef long long ll;

#define rep(i, n) for (int i = 0; i < (n); i++)
int main(void){
	int n; cin >> n;
	string s; cin >> s;
	ll h1 = 0, h2 = 0, p = 1;
	int rekord = n;
	for (int i = n-1; i >= 0; i--) {
		int x = s[i] - 'a';
		h1 = (29*h1 + x) % MOD;
		h2 = (h2 + p * x) % MOD;
		p = p*29 % MOD;
		if (h1 == h2) rekord = i;
	}
	cout << rekord << endl;
}