#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cassert>
#include <vector>
#include <string>
#include <cmath>
#include <map> 
#include <sstream>
#include <cstdio>
using namespace std;
 
const int MAX= 10000100;

#define loop(i,a,b) for(int i = a ; i < b ; i ++)
#define rep(i,a) loop(i,0,a)
#define all(a) (a).begin(),(a).end()
#define ll long long int
#define gcd(a,b) __gcd(a,b)
#define pb(a) push_back(a)
int GCD(int a, int b) {if(!b) return a; return gcd(b, a%b);}
int lcm(int a, int b) {return a*b / gcd(a, b);}

int main(void){
  int b;
  int n;
  cin>>b>>n;
  vector<int> c(n);
  int sum = 0;
  rep(i,n){
    cin>>c[i];
    sum += c[i];
  }
  int ave = sum / n;
  
  sum = 0;
  int res = int(1e9);
  rep(i,n){
    sum += abs(c[i] - ave);
  }
  res = sum;
  ave ++;
  rep(i,n){
    sum += abs(c[i] - ave);
  }
  rep(i,b/n){
  sum = 0;
  ave = ave + i - 1;
 
  sum = 0;
  rep(i,n){
    sum += abs(c[i] - ave);
  }
  res = sum;
  ave ++;
  rep(i,n){
    sum += abs(c[i] - ave);
  }
  sum = 0;

  res = min(res,sum);
  }

  cout<<res<<endl;
}