#include <bits/stdc++.h>
#define ll long long
using namespace std;

int main()
{
   ll n,k;
   cin>>n>>k;
   ll arr[n];
   for(int i=0;i<n;i++)
   cin>>arr[i];
   ll mx=1e13,sum=0;
   for(int j=0;j<n/k;j++){
       ll x=j;
       for(int i=0;i<n;i++){
          if(i!=x)
          sum+=arr[i];
          else
          x+=k;
       }
       if(mx>sum)
       mx=sum;
       sum=0;
   }
   cout<<mx;
   
      return 0;
}