#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;
typedef long long ll;

vector<int>c;
int n;
ll cnt(int a) {
	ll cnt = 0;
	for (int i = 0; i < n; i++) {
		cnt += abs(c[i] - a);
	}
	return cnt;
}

int main()
{
	int b; cin >> b >> n;
	c.resize(n);
	ll sum = 0;
	for (int i = 0; i < n; i++) {
		cin >> c[i];
		sum += c[i];
	}
	sort(c.begin(), c.end());

	ll l=c[0], r=(sum+b)/n+1;

	while (r - l > 3) {
		int ml = (l * 2 + r) / 3, mr = (l + r * 2) / 3;

		if (cnt(ml) > cnt(mr)) {
			l = ml;
		}
		else r = mr;
	}

	ll ans=cnt(l);
	for (int i = l+1; i < r; i++) {
		ans = min(ans, cnt(i));
	}
	cout << ans << endl;

    return 0;
}