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

#define endl '\n'

void io(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cout.precision(15);
}
long long dp[10001] ;
long long C[10001] ;
int main(int argc,char* argv[]) { 
    io() ;
    #ifndef ONLINE_JUDGE
        //freopen("inp.txt", "r", stdin) ;
        // freopen("out.txt", "w", stdout);
    #endif
    int k ;
    int n ;
    cin >> n >> k ;
    for(int i = 1 ; i <= n ; i++){
        cin >> C[i] ;
    }
    for(int i = 1 ; i <= n ; i++){
        dp[i] = dp[max(0,i-k-1)] + C[i];
        for(int j = i - 1 ; j >= max(1,i-k) ; j--){
            dp[i] = min(dp[i] , dp[j]) ;
        }
    }
    cout << dp[n] << endl; 
    return 0 ; 
}