#include<iostream>
#include<fstream>
#include<cmath>
using namespace std;
int k,n,s[100000],mint=1000000000,sn,i,j;
int main()
{
    freopen("walk.in","r",stdin);
    freopen("walk.out","w",stdout);
    //ios::sync_with_stdio(false);
    cin>>n>>k;
    for(i=0; i<n; i++)
        cin>>s[i];
    if(k==1)
    {
        cout<<"0\n";
        return 0;
    }
    else
    {
        for(i=0; i<=n-k; i++)
        {
            sn=0;
            for(j=i+1; j<i+k; j++)
            {
                sn+=abs(s[j]-s[j-1]);
                if(sn>=mint)
                    break;
            }
            if(sn<mint)
                mint=sn;
        }
    }
    cout<<mint<<endl;
}