n = int(input())
if n == 0:
    print(0)
else:
    a = list(map(int, input().split()))
    last_occurrence = {}
    max_len = 0
    L = 0
    for R in range(len(a)):
        num = a[R]
        if num in last_occurrence and last_occurrence[num] >= L:
            L = last_occurrence[num] + 1
        last_occurrence[num] = R
        current_len = R - L + 1
        if current_len > max_len:
            max_len = current_len
    print(max_len)