import sys
readline=sys.stdin.readline
from math import gcd as GCD

N=int(readline())
A=list(map(int,readline().split()))
r=0
se=set()
ans=0
for l in range(N):
    while r<N and not A[r] in se:
        se.add(A[r])
        r+=1
    ans=max(ans,r-l)
    se.remove(A[l])
print(ans)