#include <iostream>
#include <cstdlib>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
	int n,m;
	vector<int> dm;
	vector<int> dp;
	cin>>n>>m;
	int tmp;
	for(int i=0;i<m;i++){
		cin>>tmp;
		if(tmp<0){
		    dm.push_back(tmp);
		}else{
		    dp.push_back(tmp);
		}
	}
	dp.push_back(0);
	dm.push_back(0);
	sort(dm.begin(),dm.end(),greater<int>());
	sort(dp.begin(),dp.end());
	int distance=0;
	int garbage=n;
	int minimum=30000;
	int i;
	for(i=1;i<(int)dm.size();i++){
		distance+=abs(dm[i]);
		garbage-=i;
		if(garbage>0){
		    if(dp.size()>=garbage+1){
				distance+=abs(dp[garbage])+abs(dm[i]);
				garbage=0;
			}
		}
		if(garbage<=0&&minimum>=distance)minimum=distance;
		distance=0;
		garbage=n;
	}
	for(i=1;i<(int)dp.size();i++){
		distance+=abs(dp[i]);
		garbage-=i;
		if(garbage>0){
			if(dm.size()>=garbage+1){
			    distance+=abs(dm[garbage])+abs(dp[i]);
				garbage=0;
			}
		}
		if(garbage<=0&&minimum>=distance)minimum=distance;
		distance=0;
		garbage=n;
	}
	cout<<minimum<<endl;
}