#include<iostream.h>
#include<fstream.h>
#define N 5000001
typedef struct deque
{long elem[N],prim,ultim;};
long a,n,k,i,b[N];
long long s=0;
deque q;

int main()
{q.prim=q.ultim=0;
ifstream f1("deque.in");
ofstream f2("deque.out");
f1>>n>>k;
b[0]=0;
for(i=1;i<=n;i++)
      {f1>>a;
      while(q.ultim!=q.prim&&a<q.elem[q.ultim-1])
             q.ultim--;
      q.elem[q.ultim++]=a;
      b[q.prim]++;
      b[q.prim+1]=q.ultim-q.prim-1;
      b[q.ultim-1]=1;
      if(((q.ultim-q.prim==1&&q.prim==i-k)||(q.prim<i-k&&q.ultim-q.prim<k)||(i==k&&b[q.prim]>1))&&b[q.prim]<k)
             s+=q.elem[q.prim];
      else
             if(q.ultim-q.prim==k||b[q.prim]==k||q.prim==i-k||(i==k&&b[q.prim]==1))
                   s+=q.elem[q.prim++];}
f2<<s;
f1.close();
f2.close();
return 0;}