#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int all1[10100];
bool all2[10100] = {false};

long long int a, b, cost = 0;


int fndMin() {
    int mn = -1;
    int val = 9999999999;
    for (int i = 0; i < a; ++i) {
        if (!all2[i] && all1[i] < val) {
            val = all1[i];
            mn = i;
        }
    }
    return mn;
}

int main() {
    cin >> a >> b;
    for (int i = 0; i < a; ++i)
        cin >> all1[i];

    while (1) {
        int mn = fndMin();
        if (mn == -1) break;
        cost += all1[mn];
        for (int i2 = mn-b; i2 <= mn+b; ++i2) {
            int k = i2;
            if (k < 0) k = a + k;
            if (k >= a) k = k - a;;
            all2[k] = true;
        }
    }

    cout << cost << endl;
    return 0;
}