package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)
var rdr = bufio.NewReaderSize(os.Stdin, 1000000)

func main() {
	sc.Split(bufio.ScanWords)
	b, n := nextInt(), nextInt()
	boxes := make([]int, n)
	for i := 0; i < n; i++ {
		boxes[i] = nextInt()
	}
	sum := b
	for _, v := range boxes {
		sum += v
	}
	avg := sum / n

	min := int(1e16)
	for _, base := range append([]int{avg}, boxes...) {
		c := 0
		if base > avg {
			continue
		}

		for _, v := range boxes {
			diff := int(math.Abs(float64(base - v)))
			c += diff
		}
		if c < min {
			min = c
		}
	}
	fmt.Println(min)
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(nextLine())
	return i
}