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

struct automat {
	vector<map<char, int>> edges;
	vector<int> link;
	vector<int> length;
	vector<bool> koniec;
	
	int last;
	
	automat(string s) {
		edges.push_back({});
		link.push_back(-1);
		length.push_back(0);
		last = 0;
		
		for (int i = 0; i < (int)s.size(); i++) {
			edges.push_back({});
			length.push_back(i + 1);
			link.push_back(0);
			int r = edges.size() - 1;
			
			int p = last;
			while (p >= 0 && edges[p].find(s[i]) == edges[p].end()) {
				edges[p][s[i]]= r;
				p = link[p];
			}
			
			if (p != -1) {
				int q = edges[p][s[i]];
				if (length[p] + 1 == length[q]) {
					link[r] =  q;
				} else {
					edges.push_back(edges[q]);
					length.push_back(length[p] + 1);
					link.push_back(link[q]);
					int qq = edges.size() - 1;
					link[q] = qq;
					link[r] = qq;
					while (p >= 0 && edges[p][s[i]]== q) {
						edges[p][s[i]] = qq;
						p = link[p];
					}
				}
			}
			last = r;
		}
		
		koniec.resize(link.size(), false);
		int x = last;
		while (x) {
			koniec[x] = true;
			x = link[x];
		}
	}
};

int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	
	int n;
	string s;
	cin >> n >> s;
	automat a(s);
	
	int res = n - 1;
	int gdzie = 0;
	for (int i = n - 1; i >= 0; i--) {
		char c = s[i];
		gdzie = a.edges[gdzie][c];
		if (gdzie == 0) {
			break;
		}
		if (a.koniec[gdzie]) {
			res = i;
		}
	}
	cout << res << endl;
	
	return 0;
}