How many Portal games are there?
2
3
2
4
3
2
4
3
5
2
4
3
5
2
4
3
5
2
4
3
5
2
4
3
5
2
4
3
5
2
1
4
3
5
2
1
4
3
5
2
1
4
3
5
2
1
4
3
5
2
6
1
4
3
5
7
2
6
1
4
3
5
0
7
2
6
1
4
3
5
7
2
6
1
4
3
5
7
2
6
1
4
3
5
8
7
2
6
1
4
3
5
8
7
2
6
1
4
3
5
8
7
2
6
1
4
3
5
8
7
10
2
6
1
9
4
5
8
7
10
6
1
9
5
8
7
10
6
1
9
8
7
11
10
6
1
9
8
7
11
10
6
1
9
8
7
11
10
6
1
9
13
8
7
11
10
6
12
1
9
13
8
7
11
10
6
12
1
9
13
14
16
8
7
11
10
6
12
9
13
14
16
8
7
11
10
6
12
9
13
14
16
8
11
62
66
256
512
59
58
112