size_t -> int
Update symbolic_expression.cc

'Segment Fault' arises when '\n' is the delimiting character. Note that the delimiting character ('\n') is discarded and not written to buf when the function getline is called at line 79. And a null character ('\0') is automatically appended to buf. So I think the delimiting character should be '\0'
Merge branch 'patch-2' of https://github.com/dqx/crest-z3
Merge branch 'patch-1' of https://github.com/dqx/crest-z3
Merge branch 'master' of github.com:heechul/crest-z3