n = int(input())
if n == 0:
    print(0)
    exit()
a = list(map(int, input().split()))
max_length = 0
last_occurrence = {}
l = 0
for r in range(len(a)):
    current = a[r]
    if current in last_occurrence and last_occurrence[current] >= l:
        l = last_occurrence[current] + 1
    last_occurrence[current] = r
    current_length = r - l + 1
    if current_length > max_length:
        max_length = current_length
print(max_length)