I think this problem can be solved easily by using DFS algo. But there's sth I wantwd to ask. if our program is reading from the standard input, Can we use eof(f) in paskal? what should we do then? is it OK to use ASSIGN procedure for a file which has been made beore? I think it takes CRASH(ACCES VIOLATION) error. Is there anyone who can help me on the spot?!!

I had the same problem, because I read char and if it was 'B', I go to next stage. It was always OK except this case:

100
BLOOD
1
2

I didn't eat the newline after 100, however I always did after numbers that went after it. Anyway - this is why test 4 is special. Hope that helps :-D