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

int main()
{
    int n;
    cin >> n;
    while(n--)
    {
        int m;
        cin >> m;
        vector<pair<int, int>> v;
        for(int i=0; i<m; i++)
        {
            int x1, x2;
            cin >> x1 >> x2;
            v.push_back({x1, x2});
        }
        sort(v.begin(), v.end());
        vector<pair<int, int>> v1;
        v1.push_back(v[0]);
        for(int i=1; i<m; i++)
        {
            for(auto &t: v1)
            {
                if(v[i].first > t.second)
                {
                    v1.push_back(v[i]);
                    break;
                }
                else
                {
                    t.second = max(t.second, v[i].second);
                    break;
                }
            }
        }
        int sum = 0;
        for(auto t: v1)
        {
            sum += t.second - t.first + 1;
        }
        cout << min(sum, m) << endl;
    }
    return 0;
}