#include <bits/stdc++.h>

using namespace std;

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

int n,k;
int a[5000001];
int minim[5000001];
int coada[5000001],last=1,vf;
long long sum;

int main()
{
    in>>n>>k;

    for(int i=1;i<=n;i++)
        in>>a[i];

    for(int i=1;i<=n;i++)
    {
        if(coada[last]<=i-k)
            last++;

        while(last<=vf && a[ coada[vf] ]>=a[i])
            vf--;

        coada[++vf]=i;
        minim[i]=a[ coada[last] ];
    }

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

    out<<sum;

    return 0;
}