#include <bits/stdc++.h>
using namespace std;
// https://space.bilibili.com/672346917

#ifndef LOCAL
#define LOG(...) 42
#endif

#define fi first
#define se second
#define pb push_back
#define endl '\n'
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

typedef long long LL;
typedef pair <int, int> PII;

constexpr int inf = 0x3f3f3f3f;
constexpr double EPS = 1e-8;
const double PI = acos(-1);

int multi_cases = 1;

void A_SOUL_AvA () {
    int n;
    cin >> n;

    vector <PII> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i].fi >> a[i].se;
    }

    sort(all(a), [&](auto &u, auto &v) {
        return u < v;
    });

    int last = -1, ans = 0;
    for (int i = 0; i < n; i++) {
        if (i + 1 < n && a[i + 1].fi <= a[i].se) {
            break;
        }
        ans++;
    }

    cout << ans << endl;
}

int main () {
    cin.tie(nullptr)->sync_with_stdio(false);
    cout << fixed << setprecision(12);

    int T = 1;
    for (multi_cases && cin >> T; T; T--) {
        A_SOUL_AvA ();
    }

    return 0;
}