#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
const int inf = 1e9;
int n, t[maxn], c[maxn], R[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]);
    };
    R[n] = n;
    for(int i = n - 1; i >= 1; i--) {
        if(ck(i, i + 1)) {
            R[i] = R[i + 1];
        }
        else {
            R[i] = i;
        }
    }
    R[0] = R[1];
    if(R[0] == n) {
        return 1;
    }
    vector<int> f;
    for(int i = 0; i < R[0]; i++) {
        f.push_back(i);
    }
    int now = R[0];
    while(now < n) {
        bool ok = 0;
        for(int i : f) {
            if(ck(i, now + 1)) {
                ok = 1;
                break;
            }
        }
        if(!ok) {
            return 0;
        }
        f.clear();
        for(int i = now; i < R[now + 1]; i++){
            f.push_back(i);
        }
        now = R[now + 1];
    }
    return 1;
}
void work(){
    cin >> n;
    for(int i = 1; i <= n; i++) {
        cin >> t[i] >> c[i];
    }
    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;
}