Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
s = input()


def arihon_SA(T):
    rank = [0] * (n + 1)
    SA = [0] * (n + 1)
    temp = [0] * (n + 1)

    def rank_calc(i):
        res1 = rank[i]
        res2 = -1
        if i + k <= n:
            res2 = rank[i + k]
        return (res1, res2)

    for i in range(n + 1):
        SA[i] = i
        if i < n:
            rank[i] = ord(T[i])
        else:
            rank[i] = -1
    k = 1

    while k <= n:
        SA.sort(key=rank_calc)
        temp[SA[0]] = 0
        for i in range(1, n + 1):
            temp[SA[i]] = temp[SA[i - 1]]
            if rank_calc(SA[i - 1]) < rank_calc(SA[i]):
                temp[SA[i]] += 1
        rank = temp[::]
        k *= 2

    return SA


# SAとsからSA[i+1],SA[i]の共通接頭辞LCP[i]を求めたい。
# len(s)=nならlen(SA)=n+1
# LCP[0]は必ず0
def arihon_LCP(s, SA):
    num = len(s)
    rank = [0] * (num + 1)
    LCP = [-1] * (num)
    for i in range(num + 1):
        rank[SA[i]] = i
    h = 0
    LCP[0] = 0
    for i in range(num):
        j = SA[rank[i] - 1]
        if h > 0:
            h -= 1
        while j + h < num and i + h < num:
            if s[j + h] != s[i + h]:
                break
            else:
                h += 1
        LCP[rank[i] - 1] = h
    return LCP


class SegmentTree:
    ele = 10 ** 20
    func = min
    # SEG木は1-index
    # Aに関しては0-index

    def __init__(self, n):  # Aは0-idx
        self.n = n
        self.num = 2 ** ((self.n - 1).bit_length())
        self.SEG = [self.ele] * (2 * self.num)

    def search(self, idx):
        return self.SEG[idx + self.num]

    def initialize(self, A):
        for i in range(self.n):
            self.SEG[i + self.num] = A[i]
        for i in range(self.num - 1, 0, -1):
            self.SEG[i] = self.func(self.SEG[2 * i], self.SEG[2 * i + 1])

    def update(self, idx, val):
        idx += self.num
        self.SEG[idx] = val
        idx //= 2
        while idx:
            self.SEG[idx] = self.func(self.SEG[2 * idx], self.SEG[2 * idx + 1])
            idx //= 2

    def query(self, left, right):
        # maspy式。半開区間のママ処理する
        # left, rightで値を分けているのは交換法則不成立のときのため
        # 開区間→Rが奇数→右端が偶数→1ずらしてから計算
        # 　下から上への遷移は2で割る
        # juppy氏は閉区間に直していた
        resleft = self.ele
        resright = self.ele
        left += self.num
        right += self.num
        while right - left > 0:
            if left % 2 == 1:
                resleft = self.func(resleft, self.SEG[left])
                left += 1
            if right % 2 == 1:
                right -= 1
                resright = self.func(resright, self.SEG[right])
            left //= 2
            right //= 2
        return self.func(resleft, resright)


SA = arihon_SA(s)
LCP = arihon_LCP(s, SA)
ST = SegmentTree(n)
ST.initialize(LCP)
ans = 0
for i in range(n):
    for j in range(i + 1, n + 1):
        a = SA[i]
        b = SA[j]
        temp = ST.query(i, j)
        if abs(b - a) >= temp:
            ans = max(ans, temp)
print(ans)


Fixed submission:
# suffix array
# z-algorithm
# rolling-hash
# dp
n = int(input())
s = input()

# z-algorithm
# i左端
# j iからの距離
# k i-i+jの間を進みながら比較
ans = 0
for num in range(n - 1):
    S = s[num:]
    A = [0] * (n - num)
    A[0] = n - num
    i = 1
    j = 0
    while i < n - num:
        while i + j < n - num and S[j] == S[i + j]:
            j += 1
        A[i] = j
        ans = max(ans, min(i, j))
        if j == 0:
            i += 1
            continue
        k = 1
        while i + k < n - num and k + A[k] < j:
            A[i + k] = A[k]
            ans = max(ans, min(k, A[k]))
            k += 1
        i += k
        j -= k
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
# suffix array
# z-algorithm
# rolling-hash
# dp
n = int(input())
s = input()

# z-algorithm
# i左端
# j iからの距離
# k i-i+jの間を進みながら比較
ans = 0
for num in range(n - 1):
    S = s[num:]
    A = [0] * (n - num)
    A[0] = n - num
    i = 1
    j = 0
    while i < n - num:
        while i + j < n - num and S[j] == S[i + j]:
            j += 1
        A[i] = j
        ans = max(ans, min(i, j))
        if j == 0:
            i += 1
            continue
        k = 1
        while i + k < n - num and k + A[k] < j:
            A[i + k] = A[k]
            ans = max(ans, min(k, A[k]))
            k += 1
        i += k
        j -= k
print(ans)


Fixed submission:
# suffix array
# z-algorithm
# rolling-hash
# dp
n = int(input())
s = input()

# z-algorithm
# i左端
# j iからの距離
# k i-i+jの間を進みながら比較
ans = 0
for num in range(n - 1):
    S = s[num:]
    A = [0] * (n - num)
    A[0] = n - num
    i = 1
    j = 0
    while i < n - num:
        while i + j < n - num and S[j] == S[i + j]:
            j += 1
        A[i] = j
        ans = max(ans, min(i, j))
        if j == 0:
            i += 1
            continue
        k = 1
        while i + k < n - num and k + A[k] < j:
            A[i + k] = A[k]
            ans = max(ans, min(k, A[k]))
            k += 1
        i += k
        j -= k
print(ans)