#include <fstream>
#include <deque>
#define NMAX 11000000
using namespace std;
ifstream in("deque.in");
ofstream out("deque.out");

deque <int> dque;
long long N, K, S, mind = NMAX;

int main(){
   	in >> N >> K;

   	long long numar, counter = 0, poz;
   	for(int i = 1; i<=N; i++){
   		in >> numar;
   		dque.push_front(numar);
   		if(numar < mind && counter <= K){
   			mind = numar;
   			counter = 0;
   			poz = i;
   		}
   		else{
   			mind = NMAX;
   			dque.pop_back();
   			for(int i = 0; i<K; i++)
   				if(dque[i] < mind)
   					mind = dque[i];
   			counter = 0;
   			poz = i;
   		}
   		++counter;
   		if(i >= K)
   			S+=mind;
  	}
  	out << S;
  	return 0;
}