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


int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n,k;
    cin>>n>>k;
    vector<ll> a(n);
    for(int i = 0;i<n;i++) cin>>a[i];
    ll ans = 1e18;
    priority_queue<ll> que;
    priority_queue<ll> q1;
    vector<ll> use(n,1e18);
    ll sum = 0;
    if(k==1){
        cout<<a[0]<<endl;
        return 0;
    }
    for(int i = n - 1;i>=0;i--){
        use[i] = a[i];
        if(i+1<n) use[i] = min(use[i],use[i+1]);
        if(i<k-1) break;
        ll need = (i+k-2)/(k-1);
        while(que.size()+1>need){
            sum -= que.top();
            que.pop();
        }
        if(que.size()+1==need){
            if(que.empty()){
                ans = min(ans,a[i]);
            }else{
                ll mx = need * k;
                mx--;
                if(mx<n){
                    if(que.top()<use[mx]){
                        ans = min(ans,sum+a[i]-que.top()+use[mx]);
                    }else{
                        ans = min(ans,sum+a[i]);
                    }
                }
            }
        }
        sum += a[i];
        que.push(a[i]);
    }
    cout<<ans<<endl;
}