#include<fstream.h>
#define N 5000001
long a,n,k,i,b[N],q[N],p,u;
long long s=0;
int main()
{b[0]=p=u=0;
ifstream f("deque.in");
ofstream g("deque.out");
f>>n>>k;
for(i=1;i<=n;i++)
      {f>>a;
      while(u!=p&&a<q[u-1])
             u--;
      q[u++]=a,b[p]++;
      if(u-p>1)
             b[p+1]++;
      b[u-1]=1;
      if(((u-p==1&&p==i-k)||(p<i-k&&u-p<k)||(i==k&&b[p]>1))&&b[p]<k)
             s+=q[p];
      else
             if(u-p==k||b[p]==k||p==i-k||(i==k&&b[p]==1))
                     s+=q[p++];}
g<<s;
f.close();
g.close();
return 0;}