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

#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

const int N = 1e6 + 7;

int n, T[N];
string buf;
char s[N];

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);

	cin >> n >> buf;
	string rbuf = buf;
	reverse(all(rbuf));
	buf = rbuf + "#?" + buf;
	n = sz(buf);
	//cerr << buf << "\n";
	for(int i = 0; i < n; i++)
		s[i + 1] = buf[i];
		
	for(int i = 2; i <= n; i++)
	{
		int t = T[i - 1];
		while(t > 0 && s[i] != s[t + 1])
		{
			t = T[t];
		}
		if(s[i] == s[t + 1])
			t++;
		T[i] = t;
		//cerr << i << " " << T[i] << "\n";
	}
	cout << (n - 2) / 2 - T[n] << "\n";
	return 0;
}