B'You are given an array consisting of n integers a_1 , a_2 , ..., a_n . Initially a_x = 1 , all other elements are equal to 0 . You have to perform m operations. During the i -th operation, you choose two indices c and d such that l_i <= c, d <= r_i , and swap a_c and a_d . Calculate the number of indices k such that it is possible to choose the operations so that a_k = 1 in the end. The first line contains a single integer t ( 1 <= t <= 100 ) -- the number of test cases. Then the description of t testcases follow. The first line of each test case contains three integers n , x and m ( 1 <= n <= 10^9 ; 1 <= m <= 100 ; 1 <= x <= n ). Each of next m lines contains the descriptions of the operations; the i -th line contains two integers l_i and r_i ( 1 <= l_i <= r_i <= n ). For each test case print one integer -- the number of indices k such that it is possible to choose the operations so that a_k = 1 in the end. In the first test case, it is possible to achieve a_k = 1 for every k . To do so, you may use the following operations: In the second test case, only k = 1 and k = 2 are possible answers. To achieve a_1 = 1 , you have to swap a_1 and a_1 during the second operation. To achieve a_2 = 1 , you have to swap a_1 and a_2 during the second operation. '...