package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	var n int
	var T int64
	fmt.Fscan(in, &n, &T)
	var s string
	fmt.Fscan(in, &s)

	v := make([]int64, n)
	for i := 0; i < n; i++ {
		v[i] = int64(1) << (s[i] - 'a')
	}

	D := T - v[n-1] + v[n-2]
	var sum int64 = 0
	counts := make([]int, 26)
	for i := 0; i < n-2; i++ {
		sum += v[i]
		counts[s[i]-'a']++
	}

	rem := sum - D
	if rem < 0 || rem%2 != 0 {
		fmt.Println("No")
		return
	}
	rem /= 2

	for i := 25; i >= 0; i-- {
		val := int64(1) << i
		for counts[i] > 0 && rem >= val {
			rem -= val
			counts[i]--
		}
	}

	if rem == 0 {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}