#include <stdio.h>
int N,K,A[500],min,suma,start=1,end;

void deque()
{
	while (end<N)
	{
		if(A[end]<min)
		{
			suma+=A[end];
			min=A[end];
		}
		else
		{
			min=A[start];
			for(int i=start;i<=end;i++)
				if(A[i]<=min)
					min=A[i];
					
			suma+=min;
				
		}
		end++;
		start++;
}

}

int main()
{
FILE *R,*W;
R=fopen("deque.in","r");
W=fopen("deque.out","w");
fscanf(R,"%d",&N);
fscanf(R,"%d",&K);
for(int i=0;i<N;i++)
	fscanf(R,"%d",&A[i]);
min=A[0];
for(int i=0;i<K;i++)
	if(A[i]<=min)
		min=A[i];
suma+=min;
end=K;
deque();
fprintf(W,"%d",suma);
fclose(R);
fclose(W);
return 0;
}