How many books are in the Dark Tower series?
13
4
5
4
8
5
4
8
5
4
8
5
4
8
5
4
8
5
4
8
5
6
4
8
5
6
4
8
7
5
6
4
8
7
5
6
4
8
7
5
6
4
8
7
5
6
3
4
8
7
5
6
3
4
8
7
5
6
3
4
8
7
5
6
3
4
8
7
5
6
9
3
4
8
7
5
6
9
3
4
8
7
5
6
9
3
4
8
7
5
6
9
3
4
8
7
5
6
10
9
3
2
8
7
6
10
9
3
2
7
6
10
9
3
2
7
6
10
9
3
2
7
6
10
9
3
2
7
6
10
9
3
2
7
6
10
9
3
2
7
10
9
3
2
7
10
9
3
2
10
9
3
2
11
10
9
3
2
11
1
10
9
3
2
11
1
10
9
2
11
1
10
9
2
11
1
10
9
2
11
1
10
9
2
11
1
10
2
11
1
10
2
11
12
1
10
2
11
12
1
10