#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=1010;
int n,m,a[N];
int ans=1e9;
signed main(){
//	freopen("clean.in","r",stdin);
//	freopen("clean.out","w",stdout);
	cin>>n>>m;
	for(int i=1;i<=m;i++)cin>>a[i];
	sort(a+1,a+m+1);
	for(int l=1;l<=m;l++)
		for(int r=l+n-1;r<=m;r++)
			ans=min(ans,min(abs(a[l])+abs(a[l]-a[r]),abs(a[r])+abs(a[r]-a[l])));
	cout<<ans<<"\n";
	return 0;
}