package main

import "fmt"

func max(x, y int) int {
    if x < y {
        return y
    }
    return x
}

func main() {
    var n int
    fmt.Scanf("%d", &n)

    nums, exists := make([]int, n), make(map[int]int)
    for i := 0; i < n; i++ {
        fmt.Scanf("%d", &nums[i])
    }

    exists[nums[0]] = 0
    anchor, res := 0, 1
    for cur := anchor; cur < len(nums); cur++ {
        if idx, ok := exists[nums[cur]]; ok {
            for anchor <= idx {
                delete(exists, nums[anchor])
                anchor++
            }
        }
        exists[nums[cur]] = cur
        res = max(res, cur-anchor+1)
    }

    fmt.Println(res)
}