N = int(input())
A = list(map(int, input().split()))
S = set()
r = 0
ans = 0
for l in range(N):
    while r < N and A[r] not in S:
        S.add(A[r])
        r += 1
    
    if ans < r-l:
        ans = r-l
    
    if l == r:
        r += 1
    else:
        S.remove(A[l])
print(ans)