n=int(input())
ns=list(map(int,input().split()))
dic={}
s=set()
cnt=0
ans=0
r=0

for i in range(n):
    if ns[i] not in dic:
        dic[ns[i]] = 1
        cnt += 1
        ans=max(ans,cnt)
    else:
        dic[ns[i]] += 1
        s.add(ns[i])
        while s:
            if ns[r] in s:
                dic[ns[r]] -= 1
                s=set()
                r+=1
            else:
                dic[ns[r]] -= 1
                if dic[ns[r]] == 0:
                    del dic[ns[r]]
                r+=1
        cnt = (i+1) - r

        
print(ans)