#include<bits/stdc++.h>

using namespace std;

ifstream f("deque.in");
ofstream g("deque.out");

int n,k,a[5000001],minim[5000001],coada[5000001],ultimul=1,varf;
long long sum;

int main()
{
    f>>n>>k;
    for(int i=1;i<=n;i++)
        f>>a[i];

    for(int i=1;i<=n;i++)
    {
        if(coada[ultimul]<=i-k)
            ultimul++;
        while(ultimul<=varf && a[coada[varf]]>=a[i])
            varf--;
        coada[++varf]=i;
        minim[i]=a[coada[ultimul]];
    }

    for(int i=k;i<=n;i++)
        sum+=minim[i];

    g<<sum;

    return 0;
}