#include<iostream>
#include <fstream>
#include <list>
#define Parcurg( C, it ) \
    for( typeof(C.begin()) it = C.begin(); it != C.end(); it++ )
using namespace std;
int n, k, s=0, x, c=0, minim=0;
list<int> l;

int main(){
    ifstream f("deque.in");
    f>>n>>k;
    while(c++<k)
        f>>x, l.push_back(x);

    while(f>>x){
        minim=*l.begin();
        Parcurg(l, it)
            minim=min(minim, *it);
        s+=minim;
        l.pop_front();
        l.push_back(x);
    }
    minim=*l.begin();
    Parcurg(l, it)
        minim=min(minim, *it);
    s+=minim;
    l.pop_front();
    l.push_back(x);
    ofstream g("deque.out");
    g<<s;


    return 0;
}