#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>

#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<30
#define pb push_back
#define mp make_pair

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

int main() {
    int b,n;
    cin >> b >> n;

    ll sum = 0;
    vector<int> v(n);
    rep(i,n) {
        cin >> v[i];
        sum += v[i];
    }

    int ans = 0;
    if(sum%n == 0) {
        int mid = sum/n;
        rep(i,n) {
            ans += abs(mid-v[i]);
        }
    } else if(n - (sum%n) <= b) {
        int mid = sum/n + 1;
        rep(i,n) {
            ans += abs(mid-v[i]);
        }
    } else {
        int mid = sum/n;
        rep(i,n) {
            ans += abs(mid-v[i]);
        }
    }

    cout << ans << endl;

    return 0;
}