#include <bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;
typedef pair<int, int> PII;
const int N = 1000010;
unordered_map<int, int> mp;
PII q[N];
void solve()
{
    int n;
    cin >> n;
    priority_queue<PII, vector<PII>, greater<PII>> heap;
    for (int i = 1; i <= n; i++)
    {
        cin >> q[i].first >> q[i].second;
        heap.push(q[i]);
    }
    int res = 0;
    int now = 0;
    while (heap.size())
    {
        int l = heap.top().second, r = heap.top().second;
        if (now < l)
            now = l;
        for (int i = now; i <= r; i++)
        {
            if (!mp[i])
            {
                mp[i] = 1;
                res++;
                break;
            }
        }
        heap.pop();
    }
    cout << res << endl;
    mp.clear();
}
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int T = 1;
    cin >> T;
    while (T--)
    {
        solve();
    }
    return 0;
}