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

int main(){
	long long b,n;
	cin >> b >> n;
	vector<long long> c(n);
	for(auto &a:c) cin >> a,b += a;
	sort(c.begin(),c.end());
	long long ans = 0;
	for(int i = 0; i < n; i++) ans += abs(c[i] - min(b/n,c[n/2]));
	cout << ans << endl;
	return 0;
}