#include <bits/stdc++.h>
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define i64 long long
#define endl '\n'
#define lb(x) ((x) & (-x))
using namespace std;
const i64 mod = 1e15+7;
const int maxn = 1e3+10;
signed main()
{
    IOS;
    int t; cin >> t;
    while(t--)
    {
        int n; cin >> n;
        vector<pair<int,int>> v(n+1);
        vector<int> s;
        for(int i = 1; i <= n; ++i)
        {
            cin >> v[i].first >> v[i].second;
            s.push_back(v[i].first);
            s.push_back(v[i].second);
            s.push_back(v[i].first - 1);
            s.push_back(v[i].first + 1);
            s.push_back(v[i].second - 1);
            s.push_back(v[i].second + 1);
        }
        sort(v.begin() + 1,v.end());
        sort(s.begin(),s.end());
        int len = unique(s.begin(),s.end()) - s.begin();
        int ans = 0,now = 1;
        priority_queue<pair<int,int>> q;
        for(int i = 0; i < len; ++i)
        {
            while(now <= n && v[now].first <= s[i])
            {
                q.push({-v[now].second,-v[now].first});
                now++;
            }
            while(q.size() && -q.top().first < s[i]) q.pop();
            if(q.size())
            {
                ans++;
                q.pop();
            }
        }
        cout << ans << endl;
    }
    return 0;
}