import sys
input = sys.stdin.readline

from collections import deque

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

USE=[0]*1000001

ANS=0
Q=deque()
for a in A:
    if USE[a]==1:
        while USE[a]==1:
            x=Q.popleft()
            USE[x]-=1

    USE[a]=1
    Q.append(a)
    ANS=max(ANS,len(Q))

print(ANS)