#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const int maxn = 1e6 + 5;
const int inf = 1e9;
int n, t[maxn], c[maxn];
bool check(int v) {
	function<bool(int, int)> ck = [&](int i, int j) {
		if(i == 0) {
			return true;
		}
		return (1ll * v * (t[j] - t[i])) >= 1ll * abs(c[i] - c[j]);
	};
	vector<int> f;
	f.push_back(0);
//	cout << ck(1, 3) << '\n';
	for(int i = 1; i < n; i++) {
		if(ck(i, i + 1)) {
			continue;
		}
//		if(i == 2) {
//			for(int j : f) {
//				cout << j << ' ';
//			}
//			cout << '\n';
//		}
		bool ok = 0;
		for(int j : f) {
			if(ck(j, i + 1)) {
				ok = 1;
				break;
			}
		}
//		if(i == 2) {
//			cout << ok << "LLL\n";
//		}
		if(!ok) {
			return 0;
		}
		f.clear();
		f.push_back(i);
	}
	return 1;
}
void work(){
	cin >> n;
	for(int i = 1; i <= n; i++) {
		cin >> t[i] >> c[i];
	}
//	cout << check(2) << '\n';
//	cout << '\n';
//	return;
	int l = 0, r = inf, ans = -1;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(check(mid)) {
			ans = mid;
			r = mid - 1;
		}
		else {
			l = mid + 1;
		}
	}
	cout << ans << '\n';
}


int main(){
	
	ios::sync_with_stdio(false);
	cin.tie(0);
	int T;
	cin >> T;
	while(T--){
		work();
	}	
	return 0;
}

answer.code: In function ‘bool check(int)’:
answer.code:9:9: error: ‘function’ was not declared in this scope
    9 |         function<bool(int, int)> ck = [&](int i, int j) {
      |         ^~~~~~~~
answer.code:4:1: note: ‘std::function’ is defined in header ‘<functional>’; did you forget to ‘#include <functional>’?
    3 | #include <algorithm>
  +++ |+#include <functional>
    4 | using namespace std;
answer.code:9:31: error: expression list treated as compound expression in functional cast [-fpermissive]
    9 |         function<bool(int, int)> ck = [&](int i, int j) {
      |                               ^
answer.code:9:18: error: expected primary-expression before ‘bool’
    9 |         function<bool(int, int)> ck = [&](int i, int j) {
      |                  ^~~~
answer.code:19:20: error: ‘ck’ was not declared in this scope; did you mean ‘c’?
   19 |                 if(ck(i, i + 1)) {
      |                    ^~
      |                    c
answer.code:30:28: error: ‘ck’ was not declared in this scope; did you mean ‘ok’?
   30 |                         if(ck(j, i + 1)) {
      |                            ^~
      |                            ok