package main

import "fmt"

func main() {
	var n, m int
	fmt.Scan(&n, &m)
	shoot := make([]int, n)
	for i := range shoot {
		fmt.Scan(&shoot[i])
	}
	min, cnt := -1, 0
	ma := make([]int, m+1)
	l, r := 0, 0
	for ; r < n; r++ {
		if cnt == m {
			for ; l <= r && cnt == m; l++ {
				if min == -1 || r-l < min {
					min = r - l
				}
				if c := shoot[l]; c != 0 {
					ma[c]--
					if ma[c] == 0 {
						cnt--
					}
				}
			}
		}
		if c := shoot[r]; c != 0 {
			if ma[c] == 0 {
				cnt++
			}
			ma[c]++
		}
	}
	if cnt == m && r-l < min {
		min = r - l
	}
	fmt.Println(min)
}