#include <iostream>
#include <algorithm>
#include <vector>
#include <numeric>

using namespace std;

int main()
{
	int b, n; cin >> b >> n;
	vector<int> c(n);
	for(int i=0;i<n;++i) cin >> c[i];
	
	sort(c.begin(),c.end());
	const int mxt= (accumulate(c.begin(),c.end(),0LL)+b)/n;
	const int cts = c[n/2] > mxt? mxt: c[n/2];
	long long ans = 0;
	for(auto dt: c) ans += abs(dt - cts);
	cout << ans << endl;
	return 0;
}