#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, string> pls;

int main()
{
	ll B;  cin >> B;
	int N; cin >> N;
	ll C[12];

	ll sum = 0;
	for (int i = 0; i < N; i++) {
		cin >> C[i];
		sum += C[i];
	}

	ll ave =  (sum+B) / N,sa = 0;
	sort(C,C+N);
	reverse(C, C + N);
	ll ans = 10000000000;
	for (int i = 0; i < N; i++) {
		ll res = 0;
		ll b = B;
		ll num = C[i];
		for (int j = 0; j < N; j++) {
			if (C[j] > num) {
				b += C[j] - num;
				res += C[j] - num;
			}else if(C[j] < num){
				if (abs(C[j] - num) > b) {
					res = 1000000000000;
					break;
				}
				b -= num - C[j];
				res += num - C[j];
			}
		}
		ans = min(ans,res);
	}

	ll res = 0;
	for (int i = 0; i < N; i++) {
		if (C[i] > ave) {
			B += C[i] - ave;
			res += C[i] - ave;
		}
		else if (C[i] < ave) {
			if (abs(C[i] - ave) > B) {
				res = 1000000000000;
				break;
			}
			B -= ave - C[i];
			res += ave - C[i];
		}
	}
	ans = min(ans,res);
	
	cout << ans << endl;
	return	0;
}