n = int(input())
if n == 0:
    print(0)
else:
    a = list(map(int, input().split()))
    max_len = 0
    current_set = set()
    left = 0
    for right in range(n):
        while a[right] in current_set:
            current_set.remove(a[left])
            left += 1
        current_set.add(a[right])
        current_len = right - left + 1
        if current_len > max_len:
            max_len = current_len
    print(max_len)