#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef long double ld;
#define rep(i, a, n) for (int i = (a); i < (n); i++)
#define per(i, a, n) for (int i = (n) - 1; i >= (a); i--)
#define FOR(i, n) rep(i, a, (n))

typedef unsigned long long H;
static const H C = 123891739;
typedef H K;

struct HashInterval {
	vector<K> ha, pw;
	HashInterval(string& str) : ha(str.size()+1), pw(ha) {
		pw[0] = 1;
		rep(i,0,str.size())
			ha[i+1] = ha[i] * C + str[i],
			pw[i+1] = pw[i] * C;
	}
	H hashInterval(int a, int b) {
		return ha[b] - ha[a] * pw[b - a];
	}
};

int main(void)
{
	ios_base::sync_with_stdio(false);
	int n;
	cin >> n;
	string s;
	cin >> s;
	string sr = s;
	reverse(sr.begin(), sr.end());
	int res = n-1;

	HashInterval h1(s), h2(sr);


	rep(len,0,n) {
		//cout << "foo" << endl;
		if (n-2*len >= 0 &&
				h2.hashInterval(0, len) == h1.hashInterval(n-2*len, n-len)) {
			res = min(res, n - 2*len);
		}
		//cout << "foo" << endl;
		if (len > 0 && n-2*len+1>= 0 &&
				h2.hashInterval(0, len) == h1.hashInterval(n-2*len+1, n-len+1)) {
			res = min(res, n - 2*len+1);
		}
		//cout << "foo" << endl;
	}

	cout << res << endl;
}