#include <iostream>
using namespace std;
typedef long long ll;
int main(){
  ll b,n,c;
  cin>>b;
  cin>>n;
  ll ary[n];
  ll d=0;
  for(ll i=0; i<n; ++i){
    cin>>c;
    ary[i]=c;
    d+=c;
  }
  ll e=d/n;
  if(n>1){
    (d+b)/n;
  }
  ll f=0;
  for(ll i=0; i<n; ++i){
    ll g=e-ary[i];
    if(g<0) g*=-1;
    f+=g;
  }
  cout<<f<<endl;
  return 0;
}