n = int(input())
if n == 0:
    print(0)
    exit()
a = list(map(int, input().split()))
max_len = 0
left = 0
seen = dict()

for right in range(n):
    num = a[right]
    if num in seen and seen[num] >= left:
        left = seen[num] + 1
    seen[num] = right
    current_len = right - left + 1
    if current_len > max_len:
        max_len = current_len

print(max_len)