HDU 1050 moving tables

Description

The famous ACM (advanced computer maker) company has rented a floor of a building whose shape is in the following figure.

The floor has 200 rooms each on the North Side and south side along the corridor. recently the company made a plan to reform its system. the reform provided des moving a lot of tables between rooms. because the corridor is narrow and all the tables are big, only one table can pass through the corridor. some plan is needed to make the moving efficient. the manager figured out the following plan: moving a table from a room to another room can be done within 10 minutes. when moving a table from room I to room J, the part of the corridor between the front of room I and the front of room J is used. so, during each 10 minutes, several moving between two rooms not sharing the same part of the corridor will be done simultaneously. to make it clear the manager has strated the possible cases and impossible cases of simultaneous moving.

For each room, at most one table will be either moved in or moved out. now, the manager seeks out a method to minimize the time to move all the tables. your job is to write a program to solve the manager ?? S problem.


Input

The input consists of T test cases. the number of test cases) (T is given in the first line of the input. each test case begins with a line containing an integer N, 1 <= n <= 200, that represents the number of tables to move. each of the following n lines contains two positive integers S and T, representing that a table is to move from room number S to room number t (each room number appears at most once in the n lines ). from the N + 3-rd line, the remaining test cases are listed in the same manner as abve.

Output

The output shoshould contain the minimum time in minutes to complete the moving, one per line.


Sample Input

3
4
10 20
30 40
50 60
70 80
2
1 3
2 200
3
10 100
20 80
30 50

Output for the sample input

10
20
30

 

Question and analysis:

There are rooms numbered 1-in the first floor. The odd and even numbers are on both sides. There are some tables to move, but the corridor can only accommodate the movement of the next table for a while. (That is to say, different road sections can be carried out at the same time) There are some tables that need to be moved from one room to another and you need the shortest time required.

The greedy idea is: first sort the number of the room and find out the movement without conflict. Save conflicting moves. Then, find the non-conflicting moves from the saved moves. Until all the moves are completed.

AC code:

Another idea is to change the two numbers at the opposite door into one number. Then the numbers 1-are changed to numbers 1. Then, calculate the number of times each room's road section passes, and take the maximum value.

The Code is as follows: