How many books are in the Dark Tower series?
13
3
3
3
5
3
5
3
5
3
4
5
3
4
5
3
4
5
3
4
2
5
3
4
2
5
3
4
2
5
3
4
2
6
5
3
4
2
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
7
5
3
4
2
1
6
8
7
5
4
2
1
6
8
7
5
4
2
1
6
8
7
5
4
2
13
1
6
8
7
4
2
13
1
6
8
9
7
11
10
4
2
13
1
6
12
8
9
7
11
10
2
13
1
6
12
8
9
7
11
10
2
13
1
6
12
8
9
7
11
10
2
13
1
6
12
8
9
7
11
10
13
1
6
12
8
9
7
11
10
13
1
6
12
8
9
7
11
10
13
1
6
12
8
9
7
11
10
14
13
1
12
8
9
7
11
10
3 books
4 books