#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
typedef long long ll;

// 揃える数を決めて三分探索
ll B, N;
ll C[10];
// xで揃えた時の回数
ll llabs(ll x){
  return x > 0 ? x : -x;
}
ll calc (ll x) {
  ll ret = 0;
  FOR(i,0,N){
    ret += llabs(C[i] - x);
  }
  return ret;
}

int main(){
  cin >> B >> N;
  ll csum = 0;
  FOR(i,0,N){
    cin >> C[i];
    csum += C[i];
  }
  if(N == 1){
    cout << 0 << endl;
    return 0;
  }
  sort(C, C + N);
  ll l = C[0], r = (B + csum) / N + 1;
  while(r - l > 3){
    ll ml = (r + 2 * l) / 3;
    ll mr = (2 * r + l) / 3;
    if(ml <= mr) r = mr;
    else l = ml;
  }
  ll ans = 1000000000000000;
  for(ll i = l; i <= r; i++) ans = min(ans, calc(i));
  cout << ans << endl;
  return 0;
}