#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <climits>
#include <vector>
#include <numeric>
#include <complex>
#include <map>
using namespace std;

#define __int64 long long
#define long __int64
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
const int Vecy[4] = {0,-1,0,1};
const int Vecx[4] = {1,0,-1,0};

int n;
long c[10];

long func(long adjust){
	long score = 0;
	for(int i=0; i<n; i++){
		score += abs(c[i] - adjust);
	}
	return score;
}

int main(){
	long b;
	long sum;
	long ans = LLONG_MAX;
	long l,r;
	long max_adjust;
	
	cin >> b >> n;
	sum = b;
	for(int i=0; i<n; i++){
		cin >> c[i];
		sum += c[i];
	}
	
	max_adjust = sum / n;
	r = max_adjust;
	l = 0;
	
	//三分探索（下に凸)
	while(r - l > 2){
		if(func((l+l+r)/3) < func((l+r+r)/3)){
			r = (l+r+r)/3;
		}else{
			l = (l+l+r)/3;
		}
	}
	
	for(int i=r-3; i<=max_adjust&&i<=r+3; i++){
		ans = min(ans, func(i));
	}
	
	cout << ans << endl;
	
    return 0;
}