#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
using namespace std;

void solve198()
{
	long long B, N;
	
	cin >> B >> N;
	long long ans =1000000000000000000;
	vector<long long > BOX(N);

	long long val = 0;
	for (int i = 0; i < N; i++)
	{
		cin >> BOX[i];
		val += BOX[i];
	
	}

	val = val / N;
	vector<pair<long long,int> > goal(N);
	for (int i = 0; i < N; i++)
	{
		goal[i] = make_pair(abs(BOX[i] - val),i);
	}

	sort(BOX.begin(), BOX.end());
	reverse(BOX.begin(), BOX.end());
	
	sort(goal.begin(), goal.end());

	long long tmp = B;
	int i = 0;
	while (val != BOX[goal[1].second]){
		B = tmp;
		long long count = 0;
		val = goal[0].first + i;
		for (int i = 0; i < N; i++)
		{

			B += BOX[i] - val;
			count += abs(BOX[i] - val);

		}
		if (B >= 0){
		//	cout << val << endl;
		//	cout << count<<endl;
			ans = min(ans, count);
		}
		i++;
	}
	cout << ans << endl;
	return;
}
int main(){
	solve198();
	return 0;
}