#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
 
int main() {
	int t;
	ll n,k;
	cin>>t;
	while(t--){
		cin>>n>>k;
		ll val[n],ans[n];
		for(ll i=0;i<n;i++){
			cin>>val[i];
			ans[i]=val[i];
		}
		ll mx=val[n-k];
		for(ll x=0;x<n;x++){
			if(x-k>=0){
				ans[x]=max(ans[x],ans[x]+ans[x-k]);
				mx=(x>=n-k && ans[x]>mx) ? (mx=ans[x]) : (mx=mx);
			}
			else{
				ans[x]=val[x];
				mx=(x>=n-k && ans[x]>mx) ? (mx=ans[x]) : (mx=mx);
			}
		}
 
		cout<<mx<<endl;
	}
	return 0;
}

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

Mgo1IDMKLTM0IC0yMyAyMyA1NDUgLTEyCjUgMwozIC01IDYgMyAxMA==

2
5 3
-34 -23 23 545 -12
5 3
3 -5 6 3 10