#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
void Fast(){
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
}
void File() {
#ifndef ONLINE_JUDGE
    freopen("Input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
}
template<class T> using ordered_set = tree<pair<int,int>, null_type,less<pair<int,int>>, rb_tree_tag,tree_order_statistics_node_update>;
typedef long long ll;
#define watch(x) cout << (#x) << " = " << x << '\n'
#define endl '\n'
#define all(a)  a.begin(), a.end()
#define fix(n) cout << fixed << setprecision(n)
#define skip continue
const long double pi = acos(-1);
const int dx[] = { 1, 0, -1, 0, 1, 1, -1, -1 };
const int dy[] = { 0, 1, 0, -1, 1, -1, 1, -1 };

int main(){
    Fast();
    int n , k;cin >> n >> k;
    ll ans = 0;
    vector<int>v(n);
    for(int i = 0 ; i < n;i++){
        cin >> v[i];
        ans += v[i];
    }
    ll res = 1e18;
    for(int i = 0 ; i < n;i++){
        ll cnt = 0;
        for(int j = i ; j < n;j+=k){
            cnt += v[j];
        }
        res = min(res , ans - cnt);
    }
    cout << res << endl;
}