#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef double db;

const int N = 1e6 + 7;

int n;

struct Coin
{
    int t, p;
}a[N];

struct Seg
{
    ll l, r;
    bool empty()
    {
        return !l && !r;
    }
    void inc(ll x)
    {
        if (empty())
            return;
        l -= x;
        r += x;
    }
    bool in(int pos)
    {
        return l <= pos && pos <= r;
    }
}b[2];

bool check(ll v)
{
    b[0] = b[1] = {};
    for (int i = 1; i <= n; i++)
    {
        ll delta_t = (a[i].t - a[i - 1].t) * v;
        b[0].inc(delta_t);
        b[1].inc(delta_t);
        if (b[0].empty() || b[1].empty())
        {
            if (b[0].empty() || b[0].in(a[i].p))
                b[0] = {a[i].p, a[i].p};
            else
                b[1] = {a[i].p, a[i].p};
        }
        else
        {
            bool t1 = b[0].in(a[i].p),
                 t2 = b[1].in(a[i].p);
            if (!t1 && !t2)
                return 0;
            if (t1 && t2)
            {
                if (b[1].l <= b[0].l && b[0].r <= b[1].r)
                    b[0] = {a[i].p, a[i].p};
                else
                {
                    b[1] = {min(b[0].l, b[1].l), max(b[0].r, b[1].r)};
                    b[0] = {a[i].p, a[i].p};
                }
            }
        }
    }
    return true;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;
    cin >> T;
    while (T--)
    {
        cin >> n;
        for (int i = 1; i <= n; i++)
            cin >> a[i].t >> a[i].p;
        ll L = 0, R = 1e9, Ans = -1;
        while (L <= R)
        {
            ll mid = L + R >>1;
            if (check(mid))
                Ans = mid, R = mid - 1;
            else
                L = mid + 1;
        }
        cout << Ans << "\n";
    }
}