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

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)x.size())
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

int b, n, c[10];

int f(int x){
  int lack = 0, rem = 0;
  rep(i, 0, n){
    if(c[i] > x) rem += c[i] - x;
    else lack += x - c[i];
  }
  if(lack > rem+b) return inf;
  return lack+rem;
}

signed main(){
  cin >> b >> n;
  rep(i, 0, n) cin >> c[i];

  int l = 0, r = inf;
  while(r-l > 1){
    int m = (l+r)/2;
    if(f(l) < f(r)) r = m;
    else l = m;
  }

  if(f(l) < f(r)) cout << f(l) << endl;
  else cout << f(r) << endl;

  return 0;
}