from collections import deque

N = int(input())
A = list(map(int, input().split()))
ans = 0
ct = 0
q = deque()

for a in A:
    if a not in q:
        q.append(a)
        ct += 1
    else:
        ans = max(ans, ct)
        while q[0] != a:
            q.popleft()
            ct -= 1
        q.popleft()
        q.append(a)
ans = max(ans, ct)
print(ans)