Can anyone tell what is the correct output for this problem for the following input:


baabbbbaabaaaaa
aabbababbbaaa
b
abb

according to what is written in this thread

a --> baabbbbaabaaaaa
b --> aabbababbbaaa
start --> b
z --> aab



so starting with


b


and applying one Direct derivation


b --> aabbababbbaaa


we get


aabbababbbaaa


and since

abb

is a substring of the current string then the output should be


YES



but according to the judge solution <a href=http://www.acm.inf.ethz.ch/ProblemSetArchive/B_EU_CERC/1996/all_cerc_96.tgz>in this link</a> it is problem c it get

NO

i think the judge start from the goal and use DP it go back to the start string but i dont know why it get

NO

in that test case but i think that there is something missing in the problem text