#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 main(){
	int b,n;
	long c[10];
	long sum;
	long ans;
	long ans2;
	long adjust;
	
	cin >> b >> n;
	sum = 0;
	for(int i=0; i<n; i++){
		cin >> c[i];
		sum += c[i];
	}
	
	adjust = sum / n;
	
	//adjustmax
	ans = 0;
	for(int i=0; i<n; i++){
		ans += abs(c[i] - adjust);
	}
	
	if(b + sum >= (adjust + 1) * n){
		ans2 = 0;
		for(int i=0; i<n; i++){
			ans2 += abs(c[i] - (adjust + 1));
		}
		
		cout << min(ans, ans2) << endl;
	}else{
		cout << ans << endl;
	}
	
    return 0;
}