u can have some problems with fourth condition, like convert char to string or something like this

20. vector
1241

```
Topic id is a sequence <number>.<number>. ... <number>. All numbers are integers from a segment [1, 20] and have no leading zeroes. All topic id’s are unique.
```
try test:
1. graphs
1022
1065
2. geometry
1020
2.1. idea
1130
2.2. technique
1111 1065
1265
2.2.1. convex hull
1271
3. dynamic programming
1244
20. vector

What is the test 33?

don't understand when you want to display the result. help?