N=int(input())
A=list(map(int,input().split()))
myset =set()
front = 0
back = 0
answer = 1
while front!=N:
    if A[front] in myset:
        #print(A[front])
        tmp=front-back-1
        answer = answer if answer>tmp else tmp
        for i in range(back,front):
            if A[i]==A[front]:
                back=i+1
                break
            myset.remove(A[i])
    else:
        myset.add(A[front])
    front=front+1            
    #print(answer)
#print(back,front)
tmp=front-back
answer = answer if answer>tmp else tmp
print(answer)