/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
using namespace std;
using ll = long long;
using ld = long double;
ll mod = ll(1e9)+7;
ll inf = ll(5e18);
template<typename T1, typename T2> ll ceill(T1 a, T2 b){ return (a+b-1)/b; }
void ans(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void ans2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) for (auto vvv : vv) cout << vvv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

//
// Created by champon1020 on 2020/03/10.
//

#ifndef INCLUDE_Z_HPP
#define INCLUDE_Z_HPP

namespace Z {



    class Z_Algorithm {
    public:
        // z[i] := s[0:n] と s[i:n] の最長共通接頭辞
        vector<int> z;
        void build(string s);
    };

    void Z_Algorithm::build(string s) {
        int n = s.length();
        z.assign(n, 0);
        z[0] = n;
        int i = 1, j = 0;
        while (i < n) {
            // s[0:j] と s[i:i+j] が同一である限りインクリメント
            while (i + j < n && s[j] == s[i + j]) j++;
            z[i] = j;
            if (j == 0) {
                i++;
                continue;
            }
            // 今までに計算したz配列をコピー
            int k = 1;
            while (k < j && k + z[k] < j) {
                z[i + k] = z[k];
                k++;
            }
            i += k; j -= k;
        }
    }

}

#endif //INCLUDE_Z_HPP

using Z::Z_Algorithm;

class EWhoSaysAPun {
public:
	void solve(std::istream& in, std::ostream& out) {
	    int n;
	    string s;
	    in >> n >> s;

	    Z_Algorithm za;

	    int res = 0;
        for(int l=0; l<n; l++){
            string t = s.substr(l, n);
            za.build(t);
            for(int li=1; li<n; li++){
                chmax(res, min(za.z[li], li));
            }
	    }
        out << res << endl;
	}
};


int main() {
	EWhoSaysAPun solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 256