#include "bits/stdc++.h"
using namespace std;

 
vector<int> C;
int B, N;
long long ans;

long long calc(long long a){
	long long nokori = B;
	long long temp = 0;
	for (int i = 0; i < N; i++)
	{
		temp += abs(a - C[i]);
		nokori += C[i] - a;
	}
	if (nokori < 0) return (long long) 1e18;
	ans = min(temp, ans);
	return temp;
}

int main() {
	cin >> B;
	cin >> N;
	C = vector<int>(N);
	for (int i = 0; i < N; i++)
	{
		cin >> C[i];
	}
	ans = (long long) 1e18;
	long long low = 0;
	long long high = (int)1e9 + 2;
	while (high - low > 10){
		long long lowmid = (low + low + high) / 3;
		long long highmid = (low + high + high) / 3;
		if (calc(lowmid) <= calc(highmid)) high = highmid;
		else low = lowmid;
	}

	for (int i = max(0ll , low - 100); i < low + 100; i++)
	{
		calc(i);
	}
	cout << ans << endl;
}