N = int(input())
A = list(map(int, input().split()))
ans = 0
L = 0
R = -1
q = set()

for a in A:
    if a not in q:
        q.add(a)
        R += 1
    else:
        ans = max(ans, R-L+1)
        while A[L] != a:
            q.remove(A[L])
            L += 1
        L += 1
        R += 1
ans = max(ans, R-L+1)
print(ans)