input:

2000
1000 -1000
1000 -999
1000 -998
1000 -997
1000 -996
1000 -995
1000 -994
1000 -993
1000 -992
1000 -991
1000 -990
1000 -989
1000 -988
1000 -987
1000 -986
1000 -985
1000 -984
1000 -983
1000 -982
1000 -981
1000 -980
1000 -979
1000 -978
1000 -977
1000 -976
1000 -975
1000 -974
1000 -973
1000 -972
1000...

output:

2
2
4
2
6
2
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
10...

result:

wrong answer 3rd lines differ - expected: '2', found: '4'