#include <bits/stdc++.h>
using namespace std;

const int INF = 0x3f3f3f3f;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    vector<long long> t(n), x(n);
    for (int i = 0; i < n; i++) {
      cin >> t[i] >> x[i];
    }
    long long start = 0, end = 0, from = 0, to = 0, ans = 0;
    for (int i = 0; i < n; i++) {
      if (end <= t[i]) {
        start = t[i];
        end = t[i] + llabs(to - x[i]);
        from = to;
        to = x[i];
      }
      if (min(from, to) <= x[i] && max(from, to) >= x[i]) {
        long long arrival = start + abs(from - x[i]);
        if (t[i] <= arrival && (i == n - 1 ? true : (arrival <= t[i + 1]))) {
          ans++;
        }
      }
    }
    cout << ans << '\n';
  }
  return 0;
}