#include<fstream>
#define inf 10000001
#define dim 50000000
using namespace std;
ifstream f("deque.in");
ofstream g("deque.out");
long a[dim];
int i,j,k,nr;
int n;
int s;
long minn;
long b[dim];
int main()
{
	f>>n>>k;
	for(i=1;i<=n;i++)
		f>>a[i];
	int poz=k;
	i=1;
	while(i<=n-poz+1)
	{
		for(j=i;j<=poz+i-1;j++)
		{
			minn=a[i];
			for(k=i+1;k<=poz+i-1;k++)
				if(a[k]<minn)
					minn=a[k];
		}
		nr++;
		b[nr]=minn;
		i++;
	}
	for(i=1;i<=nr;i++)
		s=s+b[i];
	g<<s;
	return 0;
}