n = int(input())
A = list(map(int, input().split()))
j = 0
s = set()
ans = 0
for i in range(n):
    while j < n:
        if A[j] not in s:
            s.add(A[j])
            j += 1
        else:
            break
    ans = max(ans, j-i)
    if i == j:
        j += 1
    else:
        s.remove(A[i])
print(ans)