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

#define _CRT_SECURE_NO_WARNINGS

#define FOR(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

const int dy[] = { 0, 1, 0, -1 };
const int dx[] = { 1, 0, -1, 0 };

using LL = long long int;
using LD = long double;

const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vb>;

int b, n, copyB;
vi C(11, INF);
void input() {
	cin >> b >> n;
	copyB = b;
	REP(i, n) cin >> C[i];
}

int solve(int mid) {
	SORT(C);

	int ans = 0;

	FOR(i, mid, n) {
		if (C[mid] < C[i]) {
			b += C[i] - C[mid];
			ans += C[i] - C[mid];
		}
	}

	for (int i = mid; i >= 0; i--) {
		if (C[mid] > C[i]) {
			b -= C[mid] - C[i];
			ans += C[i] - C[mid];
		}
	}

	if (b < 0) {
		b = copyB;
		return solve(mid - 1);
	}
	return ans;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	input();
	cout << solve((n + 1) / 2 - 1) << endl;
	return 0;
}