#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
    ll b, n;
    cin>>b>>n;
    ll a[n];
    for (int i=0;i<n;i++) {
        cin>>a[i];
        b+=a[i];
    }
    sort(a,a+n);
    ll c=min(b/n,a[n/2]);
    ll ans=0;
    for (int i=0;i<n;i++) ans+=abs(a[i]-c);
    cout<<ans<<endl;
    return 0;
}