#include <bits/stdc++.h>
#define ll long long

using namespace std;

const int MOD = 1e9 + 7;

void solve(){
	int n, k, m;
	cin >> n >> m >> k;
	
	vector<int> a(n);
	
	int len = 0;
	ll sum = 0;
	ll ans = 0;
	for(int i = 0; i < n; i++){
		cin >> a[i];
		sum += a[i];
		len++;
		if(sum <= 0){
			len = 0;
			sum = 0;
		}
		
		ans = max(ans, (ll)(sum - (k * ceil(len * 1.0 / m))));
	}
	cout << ans << "\n";
	
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t = 1;
	cin >> t;
	
	for(int i = 1; i <= t; i++){
		solve();
	}
	return 0;
}