#include<bits/stdc++.h>
using namespace std;
const int MN = 1e6 + 5;
using s64 = long long;
const s64 inf = numeric_limits<s64>::max();
int n, t[MN], c[MN];
int m, numc[MN];
s64 T1[MN], T2[MN];
void modi(s64* T, int x, s64 v) {
    for(; x <= m; x += (x & -x))
        T[x] = min(T[x], v);
}
void modiq(s64* T, int x) {
    for(; x <= m; x += (x & -x))
        T[x] = inf;
}
s64 query(s64* T, int x) {
    s64 ret = inf;
    for(; x; x -= (x & -x))
        ret = min(ret, T[x]);
    return ret;
}
bool check(int v) {
    fill(T1, T1 + m + 1, numeric_limits<s64>::max());
    fill(T2, T2 + m + 1, numeric_limits<s64>::max());
    vector<int> tmp;
    int i = 2;
    for(i = 2; i <= n; i++) {
        if((s64)(t[i] - t[i - 1]) * v < abs(c[i] - c[i - 1])) {
            for(int j = 1; j < i; j++) {
                tmp.push_back(j);
                modi(T1, numc[j], (s64)t[j] * v - c[j]);
                modi(T2, m - numc[j] + 1, (s64)t[j] * v + c[j]);
                // cerr << j << ' ' << numc[j] << ' ' << (s64)t[j] * v - c[j] << '\n';
            }
            i++;
            break;
        }
    }
    // cerr << v << " : " << i << '\n';
    for( ; i <= n; i++) {
        bool flag = 0;
        // cerr << (s64)t[i] * v - c[i] << ' ' << query(T1, numc[i]) << " T1\n";
        // cerr << (s64)t[i] * v + c[i] << ' ' << query(T2, m - numc[i] + 1) << " T2\n";
        if((s64)t[i] * v - c[i] >= query(T1, numc[i]) || (s64)t[i] * v + c[i] >= query(T2, m - numc[i] + 1)) {
            flag = 1;
        }
        if((s64)(t[i] - t[i - 1]) * v < abs(c[i] - c[i - 1])) {
            for(int x : tmp) {
                modiq(T1, numc[x]);
                modiq(T2, m - numc[x] + 1);
            }
            tmp.clear();
        }
        // cerr << flag << " flag\n";
        if(flag) {
            tmp.push_back(i - 1);
            modi(T1, numc[i - 1], (s64)t[i - 1] * v - c[i - 1]);
            modi(T2, m - numc[i - 1] + 1, (s64)t[i - 1] * v + c[i - 1]);
        }
        if(tmp.empty()) break;
    }
    return i > n;
}
void solve() {
    cin >> n;
    vector<int> num;
    for(int i = 1; i <= n; i++) cin >> t[i] >> c[i], num.push_back(c[i]);
    sort(num.begin(), num.end());
    num.erase(unique(num.begin(), num.end()), num.end());
    m = num.size();
    for(int i = 1; i <= n; i++) numc[i] = lower_bound(num.begin(), num.end(), c[i]) - num.begin() + 1;
    int L = 0, R = 1e9 + 1, ans = -1;
    while(L <= R) {
        int mid = (L + R >> 1);
        if(check(mid)) {
            ans = mid;
            R = mid - 1;
        } else L = mid + 1;
    }
    cout << ans << '\n';
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int T = 1;
    cin >> T;
    while(T--) {
        solve();
    }
}