#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll inf=INF*INF;
const ll mod=998244353;
const ll MAX=140010;



signed main(){
    ll n,k;cin>>n>>k;
    vector<ll>a(n);
    vector<ll>s(n);

    rep(i,n)cin>>a[i];
    for(int i=n-1;i>=0;i--)a[i]-=a[0];
    s[0]=a[0];
    REP(i,1,n){
        s[i]=s[i-1]+a[i];
    }
    ll l=0;
    ll ans=0;
    rep(i,n){
        if(i<k)ans+=a[i];
        else ans-=a[i];
    }
    rep(i,n){
        while(l+k<n&&a[i]-a[l]>a[l+k]-a[i]){
            l++;
        }
        if(l)ans=min(ans,-(s[n-1]-s[l+k-1]-a[i]*(n-l-k))+(s[l+k-1]-s[i]-a[i]*(l+k-1-i))+(-s[i]+s[l-1]+a[i]*(i-l+1))-(a[i]*l-s[l-1]));
        else ans=min(ans,-(s[n-1]-s[k-1]-a[i]*(n-k))+(s[k-1]-s[i]-a[i]*(k-1-i))+(-s[i]+a[i]*(i)));
    }
    cout<<ans<<endl;
}