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

void manacher(const char* w, int n, int *p, int sh) {
	int g = 0;
	p[0] = 1 - sh;
	for (int i=1;i<n;++i) {
		p[i] = 2*g-i>=0?max(min(p[2*g-i],p[g]+g-i),0):0;
		while(i>=p[i]+sh && i+p[i]<n && w[i+p[i]]==w[i-p[i]-sh])p[g=i]++;
	}
}

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	string s;
	cin >> n >> s;
	vector<int> odd(n+1), even(n+1);
	manacher(s.data(), n, odd.data(), 0);
	manacher(s.data(), n, even.data(), 1);
	int best = 1;
	for (int i = 2; i <= n; ++i) {
		const int half = i / 2;
		if (i % 2 == 1 && odd[n - 1 - half] == half + 1)
			best = i;
		else if(i%2 == 0 && even[n-half] == half)
			best = i;
	}
	cout << n - best << '\n';
}