#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
#include <cmath>
using namespace std;
using i64 = long long;
using par = pair<i64, i64>;
const int N = 1e5 + 3;
int T;
int n, num;


void work(){
	cin >> n;
	vector<par> M(n);
	for(auto &[x, y] : M)  // t, c
		cin >> x >> y;
	auto check = [&](int v)->bool{
		vector<par> A = {{-1, 0}, {-1, 0}};
		int p = 0;
		for(auto [x, y] : M){
//			cout << A[0].first << " " << A[0].second << " ,";
//			cout << A[1].first << " " << A[1].second << "\n"; 
			if((x - A[p].first) * v >= abs(y - A[p].second) or A[p].first == -1){
				A[p] = {x, y};
				continue;
			}
			p ^= 1;
			if((x - A[p].first) * v >= abs(y - A[p].second) or A[p].first == -1)
				A[p] = {x, y};
			else return false;	
		}
		return true;
	};

	
	i64 l = 0, r = 1e9, mid, ans = -1;
	while(l <= r){
		mid = (l + r)/2;
		if(check(mid)) ans = mid, r = mid - 1;
		else l = mid + 1;
	}
	cout << ans << "\n";
}


int main(){
//	freopen("test.txt", "r", stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> T;
	while(T--){
		work();
	}	
	return 0;
}