#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int n,k;
int a[10000];
long long c;
void monika(int x,int y){
    if(x<0 || y>n)
        return;
    if(x==y)
        {
        c+=a[x];
        return;
    }
    int m=a[x];
    int j;
    for(int i=x+1;i<y;++i)
        {
        if(a[i]!=-1 && m>a[i])
            {
            m=a[i];
        }
    }
    vector<int> v;
    int z=0;
    for(int i=x;i<y;++i)
        if(a[i]==m)
        {
        v.push_back(i);
    }
    int l,r;
    mx=-2000;
    z=(x+y)/2;
    vector<int>:: iterator it=lower_bound(v.begin(),z);
    l=v.size();
    if(it==v.end())
        j=v[l-1];
    else
        j=*it;
    c+=a[j];
    a[j]=-1;
    l=1;
    while(j-l>=0 && l<k)
        {
        a[j-l]=-1;
        ++l;
    }
    r=1;
    while(r+j<n && r<k){
        a[j+r]=-1;
        ++r;
    }
    monika(0,j-l);
    monika(j+r,n);
}
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    cin>>n>>k;
    for(i=0;i<n;++i)
        cin>>a[i];
    cout<<monika(0,n);
    return 0;
}