#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

llong getval(llong avgval, vector<llong> &c) {
    llong result = 0;
    for(int i: c) result += abs(avgval - i);
    return result;
}

int main() {
    int b, n;
    cin >> b >> n;
    vector<llong> c(n);
    rep(i, n) cin >> c[i];

    llong summary = accumulate(c.begin(), c.end(), 0);
    llong maxval = (summary+b) / n;
    llong minval = summary / n;
    
    while (maxval - minval > 3) {
        llong left = (maxval - minval) / 3 + minval;
        llong right = 2*(maxval - minval) / 3 + minval;
        llong a2 = getval(left, c);
        llong a3 = getval(right, c);
        if(a2 < a3) maxval = a3;
        else minval = a2;
    }
    llong left = (maxval - minval) / 3 + minval;
    llong right = 2*(maxval - minval) / 3 + minval;
    llong a1 = getval(minval, c);
    llong a2 = getval(left, c);
    llong a3 = getval(right, c);
    llong a4 = getval(maxval, c);

    cout << min(min(min(a1, a2), a3), a4) << "\n";
}