New Employees

A company is hiring new employees. Each applicant has two ranks: a document-screening rank and an interview rank.

The company does not hire an applicant if another applicant is better in both ranks. In other words, if there exists an applicant B whose document-screening rank and interview rank are both better than applicant A's, then A cannot be hired.

Find the maximum number of new employees the company can hire while following this rule.

The first line contains the number of test cases T (1 <= T <= 20).

For each test case, the first line contains the number of applicants N (1 <= N <= 100,000). Each of the next N lines contains two integers: an applicant's document-screening rank and interview rank.

Each rank is a permutation of the integers from 1 through N with no ties. A smaller rank is better.

For each test case, print the maximum number of new employees that can be hired on its own line.