#include <bits/stdc++.h>
using namespace std;
#define int int64_t
using vi = vector<int>;
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
 
signed main() {
	ios::sync_with_stdio(0); cin.tie(0);
	int t; cin >> t; while (t--) {
		int n, m, v; cin >> n >> m >> v;
		vi a(n); for (auto& i : a) cin >> i;
		auto cal = [&] (vi f) {
			vi r(n);
			int csum = 0;
			FOR(i, 0, n) {
				csum += a[i];
				if (csum >= v) csum = 0, r[i] = 1;
				if (i) r[i] += r[i - 1];
			}
			return r;
		};
		vi p = cal(a);
		reverse(a.begin(), a.end());
		vi s = cal(a); reverse(s.begin(), s.end());
		reverse(a.begin(), a.end());
 
		vi psum = a; FOR(i, 1, n) psum[i] += psum[i - 1];
 
		if (p.back() < m) {
			cout << -1 << endl;
			continue;
		}
 
		int ans = 0;
		for (int i = 0; i < n; i++) {
			int pp = i ? p[i - 1] : 0;
			int lo = i, hi = n - 1;
			while (lo < hi) {
				int mid = (lo + hi + 1) / 2;
 
				int ss = mid == n - 1 ? 0 : s[mid + 1];
 
				if (pp + ss >= m) lo = mid;
				else hi = mid - 1;
			}
			int ss = lo == n - 1 ? 0 : s[lo + 1];
			if (pp + ss >= m) ans = max(ans, psum[lo] - (i ? psum[i - 1] : 0));
		}
		cout << ans << endl;
	}
}

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7
6 2 1
1 1 10 1 1 10
6 2 2
1 1 10 1 1 10
6 2 3
1 1 10 1 1 10
6 2 10
1 1 10 1 1 10
6 2 11
1 1 10 1 1 10
6 2 12
1 1 10 1 1 10
6 2 12
1 1 1 1 10 10