// Minimum cost to reach the final index with atmost k jumps
#include<bits/stdc++.h>
using namespace std;
 
#define ll long long
 
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll n,k;
    cin>>n>>k;
    vector<ll>cost(n+1),dp(n+1);
    for(int i=1;i<=n;i++)cin>>cost[i];
    dp[0]=0;
    for(int i=1;i<=n;i++)dp[i]=INT_MAX;
    multiset<ll>s;
    s.insert(dp[0]);
    for(int i=1;i<=n;i++){
        dp[i]=cost[i]+*s.begin();
        s.insert(dp[i]);
        if(i-k>=0){
            s.erase(dp[i-k]);
        }
    }
    cout<<dp[n];
    return 0;
}

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