N = int(input())
A = list(map(int, input().split()))

l = 0
r = 0
s = set()
mx = 0
while r < N:
    if A[r] not in s:
        s.add(A[r])
        if len(s) > mx:
            mx = len(s)
        r += 1
    else:
        while A[l] != A[r]:
            # print(l, r, s)
            s.discard(A[l])
            l += 1
        l += 1
        r += 1
print(mx)