#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<cstdlib>
#include<queue>
#include<vector>
#define ll long long
using namespace std;
ll n,m,a[100010],ans=999999999;
int main()
{
	cin>>n>>m;
	for(ll i=1;i<=n;i++)cin>>a[i];
	for(ll i=1;i<=n;i++)
	{
		ll t=i+m-1,minn=99999;
		if(t>n)break;
		if(a[i]<=0&&a[t]<=0)minn=abs(a[i]);
		if(a[i]>=0&&a[t]>=0)minn=a[t];
		if(a[i]<=0&&a[t]>=0)
		{
			if(abs(a[i])<=a[t])minn=a[t]+abs(a[i])*2;
			else minn=abs(a[i])+a[t]*2;
		}
		ans=min(ans,minn);
	}
	cout<<ans<<endl; 
	return 0;
}