//satyaki3794
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define MOD (1000000007LL)
#define LEFT(n) (2*(n))
#define RIGHT(n) (2*(n)+1)
 
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
 
ll pwr(ll base, ll p, ll mod = MOD){
ll ans = 1;while(p){if(p&1)ans=(ans*base)%mod;base=(base*base)%mod;p/=2;}return ans;
}
 
ll gcd(ll a, ll b){
    if(b == 0)  return a;
    return gcd(b, a%b);
}


int n, k;
ll arr[10004], DP[10004];


int main(){

    ios_base::sync_with_stdio(0);

    cin>>n>>k;
    for(int i=1;i<=n;i++)
    	cin>>arr[i];

    ll temp = MOD;
    for(int i=1;i<=min(k+1, n);i++){
    	temp = min(temp, arr[i]);
    	DP[i] = temp;
    }

    for(int i=k+2;i<=n;i++){
    	DP[i] = (ll)1e15;
    	for(int j=i;j>=1&&i-j<=k;j--){
    		DP[i] = min(DP[i], arr[i]+DP[max(0, j-k-1)]);
    	}
    }

    ll ans = (ll)1e15;
    for(int i=n;i>=1&&i>=n-k;i--)
    	ans = min(ans, DP[i]);

    cout<<ans;
    return 0;
}