n = int(input())
a = list(map(int,input().split()))

num = [False] * 1000001

length = 0
start = 0
best_s = 0
best_l = 0

i = 0
while i < n:
    if not num[a[i]]:
        num[a[i]] = True
        length += 1
        i += 1
    else:
        if start >= n:
            break
        while start < i and a[start] != a[i]:
            num[a[i]] = False
            start += 1
        num[a[i]] = True
        start += 1
        length = i - start + 1
        i += 1

    best_l = max(best_l, length)
    if best_l == length:
        best_s = start

print(best_l)