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: Accepted)

// ~maqsat~
/*    
**    “Anyone who has never made a mistake has never tried anything new.”
**    © Albert Einstein
*/

// #pragma GCC target ("avx2")
// #pragma GCC optimization ("Ofast")
// #pragma GCC optimization ("unroll-loops")

// #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define F first
#define S second
#define in insert
#define pb push_back
#define eb emplace_back
#define sz(x) int(x.size())
#define all(x) x.begin(), x.end()
#define count1 __builtin_popcountl
#define debug(x) cerr << (#x) << " = " << (x) << "\n"
#define ACCELERATE ios_base::sync_with_stdio(false),cin.tie(nullptr)
#define fre(f) if(fopen(f".in", "r")) freopen(f".in", "r", stdin),freopen(f".out", "w", stdout)

using namespace std;
using namespace __gnu_pbds;

using ll = long long;
using ull = unsigned long long;
// using big = __int128_t; // -10^38...10^38
using db = double;
using ld = long double;
typedef pair<int,int> ii;
typedef pair<ll,ll> pll;

template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <class T> inline void cmin(T &a, T b) { a = min(a, b); }
template <class T> inline void cmax(T &a, T b) { a = max(a, b); }

const int oo = 0x3f3f3f3f;
const ll N = 1e5 + 345;
const ll MOD = 1e9 + 7;
const ll INF = 1e10 + 9;
const db EPS = 1e-9;
const db PI = acos(-1); // 3.14159265358979323846
const int dx[] = {1, -1, 0, 0, 1, 1, -1, -1};
const int dy[] = {0, 0, 1, -1, 1, -1, -1, 1};

int dp[5010][5010];
int main() {
    fre("");
    ACCELERATE;
	
	int n;
	cin >> n;

	string s;
	cin >> s;

	int ans = 0;
	for(int i = 1; i <= n; i++) {
		for(int j = i + 1; j <= n; j++) {
			if(s[i-1] == s[j-1] && j - i > dp[i-1][j-1]) {
				dp[i][j] = dp[i-1][j-1] + 1;
				cmax(ans, dp[i][j]);
			}
		}
	}

	cout << ans;
    return 0;
}
/*
 
*/