#include "bits/stdc++.h"
using namespace std;

//a * x^2 + b * x + c >= k
long long a,b,c,k;
bool yes (long long x) {
	if ((a * (x * x) + b * x + c) >= k) return true;
	else return false;
}

int main () {
	 ios::sync_with_stdio(false);
	 cin.tie(nullptr);
	 cout.tie(nullptr);
	 int T;
	 cin >> T;
	 for (int test_case = 1; test_case <= T; ++test_case) {
		cin >> a >> b >> c >> k;
		long long l = 0,r = 1e6;
		long long res = 0;
		while (l <= r) {
			long long mid = l + (r - l) / 2; // (l + r) / 2
			if (yes(mid)) {
				r = mid - 1;
				res = mid;
			} else {
				l = mid + 1;
			}
		}
		cout << res << '\n';
	 }
	 //~ cerr << "Time elapsed :" << clock() * 1000.0 / CLOCKS_PER_SEC << " ms" << '\n';
}