#include <iostream>
#include<bits/stdc++.h>
#include<unordered_map>
#define ll long long
using namespace std;
ll mn =1e18;
int main() {
    std::ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
	int k, n;cin >> n>> k;
	vector<int>a(n);
	ll sum = 0;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
		sum += a[i];
	}
	for (int i = 0; i < k; i++) {
		ll cur = 0;
		for (int j = i; j < n; j += k) {
			cur += a[j];
		}
		mn = min(mn, sum - cur);
	}
	cout << mn;
    return 0;
}