in1.txt

8
1
0 1000
1 400

2
0 2000
2 200 400

3
100 900
1 300

4 
100 1900
1 200

5 
200 800
2 250 250

6
1200 1800
1 250 

7 
1500 500
1 800

8
1600 500
1 100