#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#include <queue>
#include <string>
#include <cmath>
#include <map>
#include <set>
#include <cassert>
#define MOD 1e9 + 7
#define eps 1e-9
#define pb push_back
#define mp make_pair
#define ft first
#define sd second
#define sz(a) a.size()
#define loop(i, n) for(long long (i) = 0; (i) < (n) ; ++ (i))
#define loopn()
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pld pair<long double, long double>
#define vii vector<int>
#define vll vector<long long>  
typedef long long ll;
typedef long double ld;

using namespace std;


/*@Sergey_Miller*/

ll dp[10002][1003];
ll dpin[10002];
ll c[10001];


void solve() {
    ll n,k;
    cin >> n >> k;
    loop(i,n) {
        cin >> c[i];
    }
    loop(i,n) {
        loop(j,k+2) {
            dp[i][j] = 1e15;
        }
        dpin[i] = 1e15;
    }

    loop(i,n) {
        if(i == 0) {
            dp[0][0] = c[0];
            dp[0][1] = 0;
            dpin[0] = c[0];
            // dpmin[0] = c[0];
            continue;
        }
        loop(j,min(i,k)) {
            dp[i][0] = min(dp[i][0], dpin[i-1-j]);
        }

        if(i >= k) {
            dpin[i] = min(dpin[i], dp[i-k][1] + c[i]);
        }
// 
        // cout << i << " dpin " << dpin[i] << endl;

        dp[i][0] = min(dp[i][0], dpin[i]);
        // cout << i << " " << 0 << " " << dp[i][0] << endl;

        loop(j,k+1) {
            if(!j) {
                continue;
            }
            if(j == 1) {
                // continue;
                // if(i >= k) {
                //     dp[i][0] = min(dp[i][0], dp[i-k][1] + c[i]);
                // } else {
                //     dp[i][0] = min(dp[i][0], c[i]);
                // }
                if(i > k)
                dp[i][1] = min(dp[i][1], dpin[i-k-1]);
            } else {
                if(j <= i) {
                    dp[i][j] = min(dp[i][j], dp[i-1][j-1]);
                }
            }
            // cout << i << " " << j << " " << dp[i][j] << endl;
            // if(j <= i)
            // dpmin[i] = min(dpmin[i], dp[i][j]);
        }
    }
    cout << dp[n-1][0] << endl;
}

int main () {
    ios::sync_with_stdio(false);
     // freopen("input.txt", "r", stdin);
 //  freopen("output.txt", "w", stdout);
    solve();
    return 0;
}