Problem:
Score : 500 points

Problem Statement

Given is a string S of length N.

Find the maximum length of a non-empty string that occurs twice or more in S as contiguous substrings without overlapping.

More formally, find the maximum positive integer len such that there exist integers l_1 and l_2 ( 1 \leq l_1, l_2 \leq N - len + 1 ) that satisfy the following:

l_1 + len \leq l_2

S[l_1+i] = S[l_2+i] (i = 0, 1, ..., len - 1)

If there is no such integer len, print 0.

Constraints

2 \leq N \leq 5 \times 10^3

|S| = N

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print the maximum length of a non-empty string that occurs twice or more in S as contiguous substrings without overlapping. If there is no such non-empty string, print 0 instead.

Sample Input 1

5
ababa

Sample Output 1

2

The strings satisfying the conditions are: a, b, ab, and ba. The maximum length among them is 2, which is the answer.
Note that aba occurs twice in S as contiguous substrings, but there is no pair of integers l_1 and l_2 mentioned in the statement such that l_1 + len \leq l_2.

Sample Input 2

2
xy

Sample Output 2

0

No non-empty string satisfies the conditions.

Sample Input 3

13
strangeorange

Sample Output 3

5

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#define _CRT_SECURE_NO_WARNING
//#include <bits/stdc++.h>
#include <algorithm>
#include <iostream>
#include <map>
#include <string>
#include <vector>
#include <queue>

// #include <stack>
// #include <queue>
// #include <set>
// #include <tuple>
// #include <list>
// #include <numeric>
// #include <random>
// #include <regex>
// #include <utility>

using namespace std;
const int INF = (int)1e9;

//#define DEBUG

void solution() {
	int n, m, q;
	cin >> n;
	string s;
	cin >> s;
	int len = n / 2;
	while (len > 0) {
		for (int i = 0; i < n - len * 2; ++i) {
			for (int j = i + len; j < n - len + 1; ++j) {
				if (s.compare(i, len, s, j, len) == 0) {
					goto answ;
				}
			}
		}
		len--;
	}
	answ: cout << len;
}

int main() {
  // freopen("input.txt", "r", stdin);
  // freopen("output.txt", "w", stdout);
	solution();
  return 0;		
}