#include <iostream>
#include <vector>
#include <cmath>

#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 B, N;
    cin >> B >> N;
    vector<long> C;
    unsigned long sum = 0;

    REP(i,N) {
        long c;
        cin >> c;
        sum += c;
        C.push_back(c);
    }
    long ave = static_cast<long>(ceil((double)sum / N));
    long less = 0, more = 0;
    for(auto c: C) {
        if (c > ave) more += c - ave;
        else if (c < ave) less += ave - c;
    }
    if (less == more) {
        cout << less * 2 << endl;
    } else {
        cout << less + more << endl;
    }

    return 0;
}