#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
#include<iostream>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include <sstream>
#include<iomanip>
#include <ctype.h>
#include <fstream>
#include <cassert>
//#include <bits/stdc++.h>
using namespace std;

//#include<bits/stdc++.h>


	
int main() {
	
	long long int b, n;
	cin >> b >> n;
	vector<long long int>w;
	long long int s = b;
	for (int i = 0; i < n; i++) {
		long long int t;
		cin >> t;
		w.push_back(t);
	}

	sort(w.begin(), w.end());
	long long int m = w[n % 2 == 0 ? n / 2 - 1 : n / 2];
	long long int x = m;
	if (s > m*n)x = s / n;
	long long int ans = 0;
	for (int i = 0; i < n; i++) {
		ans += abs(w[i] - x);
	}
	cout << ans << endl;


	return 0;
}