#include <iostream>
#include <vector>
#include <cmath>
#include <numeric>
#include <climits>

#define REP(i, n) for(int i=0;i<(n);i++)

using namespace std;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    long long int B, N;
    cin >> B >> N;
    long long int maxt = 0, mint = 0;
    vector<long long int> C;
    REP(i,N) {
        long long int c;
        cin >> c;
        C.push_back(c);
        maxt += c;
    }
    maxt += B;
    maxt /= N;

    while (maxt - mint > 2) {
        long long int len = maxt - mint + 1;
        len /= 3;
        long long int lm = mint + len;
        long long int rm = mint + len + len;

        long long int lv = 0, rv = 0;
        for(auto c: C) {
            lv += abs(c - lm);
            rv += abs(c - rm);
        }
        if (lv > rv) {
            mint = lm;
        } else {
            maxt = rm;
        }
    }
    long long int ans = LLONG_MAX;
    for (long long int i = mint; i <= maxt; ++i) {
        long long int r = 0;
        for (auto c: C) {
            r += abs(c - i);
        }
        ans = min(ans, r);
    }
    cout << ans << endl;

    return 0;
}