#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()
{
    cin>>n>>k;
    for(int i=1;i<=n;i++)
        cin>>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];
 
    cout<<sum;
 
    return 0;
}