package main

import . "fmt"
import . "sort"

func main() {
	var n,k int
	Scan(&n,&k)
	a:=make([]int,n+1)
	for _=range a {
		var v int
		Scan(&v)
		a[v]++
	}
	Ints(a)
	var c int
	for ;n>0&&k>0;n-- {
		c++
		k-=a[n]
	}
	Println(c)
}