#include<bits/stdc++.h>
using namespace std;

#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define rep(i,n,m) for(int i = (n); i < (int)(m); i++)
#define rrep(i,n,m) for(int i = (m) - 1; i >= (int)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const int INF = (int)1e9+1;
template<typename T>
bool chmin(T &a,T b){if(a>b){a=b;return true;}else return false;}
template<typename T>
bool chmax(T &a,T b){if(a<b){a=b;return true;}else return false;}
template<typename T>
vector<ll>dx={1,0,-1,0,1,1,-1,-1};
vector<ll>dy={0,1,0,-1,1,-1,1,-1};
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  int n,k;
  cin>>n>>k;
  assert(1<=n&&n<=200000);
  assert(1<=k&&k<=n);
  vector<int>a(n);
  rep(i,0,n){
    cin>>a[i];
    assert(1<=a[i]&&a[i]<=(int)1e9);
  }
  if(k==1){
    cout<<a[0]<<endl;
    return 0;
  }
  priority_queue<int>que;
  ll sum=0;
  ll res=INF;
  vector<int>b(n,INF);
  b[n-1]=a[n-1];
  rrep(i,0,n-1)b[i]=min(b[i+1],a[i]);
  rrep(i,k-1,n){
    int m=(i+k-2)/(k-1);
    if(m==1){
      chmin(res,(ll)a[i]);
    }
    else if(m*k<=n){
      while(que.size()>m-1){
        sum-=que.top();
        que.pop();
      }
      if(b[m*k-1]<=que.top())chmin(res,a[i]+sum);
      else chmin(res,a[i]+sum-que.top()+b[m*k-1]);
    }
    que.push(a[i]);
    sum+=a[i];
  }
  cout<<res<<endl;
  return 0;
}