### BUGGY CODE ###

# -*- coding: utf-8 -*-
import sys
from collections import Counter, defaultdict
buff_readline = sys.stdin.buffer.readline
readline = sys.stdin.readline


class RollingHash():
    """
    Original code is https://tjkendev.github.io/procon-library/python/string/rolling_hash.html
    """
    class RH():
        def __init__(self, s, base, mod):
            self.base = base
            self.mod = mod
            self.rev = pow(base, mod-2, mod)

            l = len(s)
            self.h = h = [0]*(l+1)
            tmp = 0
            for i in range(l):
                num = ord(s[i])
                tmp = (tmp*base + num) % mod
                h[i+1] = tmp

            self.pw = pw = [1]*(len(s)+1)
            v = 1
            for i in range(l):
                pw[i+1] = v = v * base % mod

        def calc(self, l, r):
            return (self.h[r] - self.h[l] * self.pw[r-l]) % self.mod

    @staticmethod
    def gen(a, b, num):
        import random
        result = set()
        while 1:
            while 1:
                v = random.randint(a, b)//2*2+1
                if v not in result:
                    break
            for x in range(3, int(math.sqrt(v))+1, 2):
                if v % x == 0:
                    break
            else:
                result.add(v)
                if len(result) == num:
                    break
        return result

    def __init__(self, s, rand=False, num=5):
        if rand:
            bases = RollingHash.gen(2, 10**3, num)
        else:
            assert num <= 10
            bases = [641, 103, 661, 293, 547, 311, 29, 457, 613, 599][:num]

        MOD = 10**9+7
        self.rhs = [self.RH(s, b, MOD) for b in bases]

    def calc(self, l, r):
        return tuple(rh.calc(l, r) for rh in self.rhs)


def slv(N, S):
    srh = RollingHash(S, num=5)
    h2i = defaultdict(list)
    for i in range(N):
        for j in range(i+1, N+1):
            h = srh.calc(i, j)
            h2i[h].append((i, j))

    ans = 0
    for l in h2i.values():
        n = l[0][1] - l[0][0]
        l0 = l[0][0]
        for i in range(1, len(l)):
            m = l[i][0] - l0
            if m >= n:
                ans = max(ans, n)
                break
    return ans


def main():
    N = int(input())
    S = input()
    print(slv(N, S))


if __name__ == '__main__':
    main()


### FIXED CODE ###

# -*- coding: utf-8 -*-
import bisect
import heapq
import math
import random
import sys
from collections import Counter, defaultdict, deque
from decimal import ROUND_CEILING, ROUND_HALF_UP, Decimal
from functools import lru_cache, reduce
from itertools import combinations, combinations_with_replacement, product, permutations
from operator import add, mul, sub

sys.setrecursionlimit(100000)
input = sys.stdin.readline


def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def read_float():
    return float(input())


def read_float_n():
    return list(map(float, input().split()))


def read_str():
    return input().strip()


def read_str_n():
    return list(map(str, input().split()))


def error_print(*args):
    print(*args, file=sys.stderr)


def mt(f):
    import time

    def wrap(*args, **kwargs):
        s = time.time()
        ret = f(*args, **kwargs)
        e = time.time()

        error_print(e - s, 'sec')
        return ret

    return wrap

@mt
def slv(N, S):
    dp = [[0] * (N+1) for _ in range(N+1)]

    for i in range(N-1, -1, -1):
        for j in range(N-1, -1, -1):
            if S[i] == S[j]:
                dp[i][j] = dp[i+1][j+1] + 1
    
    ans = 0
    for i in range(N):
        for j in range(i+1, N):
            ans = max(ans, min(j-i, dp[i][j]))

    return ans


def main():
    N = read_int()
    S = read_str()
    print(slv(N, S))


if __name__ == '__main__':
    main()