Who can tell me…………
Why got WA#12?

if you have to cut a word, the word must end with string1+string2 (without '-'). Therefore I used:
String h=word.toUpperCase();
String s=(string1+string2).toUpperCase();
if (h.endsWith(s)){
int z=h.lastIndexOf(s) //<-- !!!
...

This helped me (in Java) to avoid WA#12.

Following test helped me to pass test #12:

0
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.