N=int(input())
A=list(map(int,input().split()))
B=[False for i in range(1000001)]

right=-1
length=0
anser=-1
for left in range(N):
    if B[A[left]]:
        while B[A[left]]:
            right+=1
            B[A[right]]=False
    
    B[A[left]]=True
    anser=max(anser,left-right)
print(anser)