#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int OO = 1e9+7 ,N=2e5+5;

int dx[] = { 0, 0, 1, -1, 1, -1, 1, -1 }; // dir array
int dy[] = { 1, -1, 0, 0, 1, -1, -1, 1 };
void File(){
#ifndef ONLINE_JUDGE
    freopen("Input.txt", "r", stdin);
    freopen("Output.txt", "w", stdout);
#endif
}

int solve(){
    int n,k;cin>>n>>k;
    int a[1000];
    ll sum=0,mn=1e18;
    for(int i=0;i<n;i++){
        cin>>a[i];
        sum+=a[i];
    }
    for(int i=0;i<n;i++){
        ll res=sum;
        for(int j=i;j<n;j+=k){
            res-=a[j];
        }
        mn =min(mn,res);
    }
    cout<<mn;
    return 0;
}
int main() {
    File();
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
//    int t,i=1;cin>>t;
//    while(t--)
        solve();

}
//Solve on paper first
//Overflooooooow
//Reverse Thinking
//If there's an equation, transform it into an easy one
//READ ALL PROBLEMS
//Verify Your thought before Coding