#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <iomanip>
#include <array>
#include <numeric>
#include <regex>
#include <bitset>
#include <deque>

using namespace std;
typedef long long ll;
typedef pair<int, int> p_ii;

const int INF = 1e9;
const double PI = acos(-1.0);
const ll MOD = 1e9 + 7;

ll c[15];

int main() {
    ll b, n;
    cin>>b>>n;
    for (int i = 0; i < n; i++) {
        cin>>c[i];
        b+=c[i];
    }
    b/=n;
    sort(c,c+n);
    ll ta=c[n/2];
    ta=min(ta, b);

    ll res=0;
    for (int i = 0; i < n; i++) {
        res+=abs(c[i]-ta);
    }

    cout<<res<<endl;

    return 0;
}