#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
using namespace std;
#define		_Narutoo ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define		all(a) a.begin(), a.end()
#define		rall(a) a.rbegin(), a.rend()
#define		endl "\n"
#define		ll long long
#define		uniquee(v) v.resize(unique(v.begin(),v.end())-v.begin())
ll      	OO = 1073741824;
ll gcd(ll x, ll y) { return(!y ? x : gcd(y, x%y)); }
ll lcm(ll x, ll y) { return x / gcd(x, y)*y; }
void File() {
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}
int main()
{
	_Narutoo;
	File();
	ll t = 1;
	//cin >> t;
	while (t--)
	{
		ll n, k, sum = 0, cnt1 = 0, cnt2 = 0;
		cin >> n >> k;
		vector<ll>v(n);
		for (auto &it : v)
		{
			cin >> it; sum += it;
		}
		ll mini = INT_MAX,cnt=0;
		for (int i = 0; i < n; i ++)
		{
			for (int j = i; j < n; j += k)
				cnt += v[j];
			mini = min(sum - cnt, mini);
			cnt = 0;
		}
		cout << mini << endl;
	}
}