The first line of input contains the number of test cases T. The descriptions of the test cases
follow:
The first line of each test case contains an integer 'n (2< = N < 100000) - the number ofvertices on
the chain.Each of the following n lines contains integer coordinates xi, Yi of the vertex Pi (0 < xi
<X2 < ... < Xn≤ 109; 0 < Yi < 10^9).