#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Vi = vector<int>;
using Pii = pair<int,int>;
#define mp make_pair
#define pb push_back
#define x first
#define y second
#define rep(i,b,e) for(int i = (b); i < (e); i++)
#define each(a, x) for(auto& a : (x))
#define all(x) (x).begin(),(x).end()
#define sz(x) int((x).size())

constexpr int ALPHA = 26;

struct PalTree {
	Vi txt;
	Vi len{0, -1};
	Vi link{1, 0};
	vector<array<int, ALPHA>> to{ {}, {} };
	int last{0};

	int ext(int i) {
		while (len[i]+2 > sz(txt) || txt[sz(txt)-len[i]-2] != txt.back())
			i = link[i];
		return i;
	
	}

	void add(int x) {
		txt.pb(x);
		last = ext(last);
		if (!to[last][x]) {
			len.pb(len[last]+2);
			link.pb(to[ext(link[last])][x]);
			to[last][x] = sz(to);
			to.emplace_back();
		}
		last = to[last][x];
	}
};

int main() {
	cin.sync_with_stdio(0); cin.tie(0);
	cout << fixed << setprecision(12);

	int n; cin >> n;
	string s; cin >> s;

	PalTree pal;

	each(c, s) {
		pal.add(c-'a');
	}

	int maxSuf = pal.len[pal.last];
	cout << n-maxSuf << endl;
	return 0;
}