#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;
	//範囲[l,r)
	while (r - l > 1) {
		int mid = (l + r) / 2;

		if (cnt(mid) < cnt(mid-1)) {
			l = mid;
		}
		else r = mid;
	}

	cout << cnt(l) << endl;

    return 0;
}