import array


def solve(n, d):
    l = r = m = 0
    c = array.array("i", [False] * (10 ** 6 + 1))

    while r < n:
        if c[d[r]]:
            m = max(m, r - l)
            c[d[l]] = False
            l += 1
        else:
            c[d[r]] = True
            r += 1
    return max(m, r - l)


n = int(input())
d = array.array("i", map(int, input().split()))

print(solve(n, d))