/in/foo.cc:4:29: warning: multi-character character constant [-Wmultichar]
 t = raw_input().replace('^','**')
                             ^
/in/foo.cc:8:38: warning: multi-character character constant [-Wmultichar]
     s.append(raw_input().replace('^','**'))
                                      ^
/in/foo.cc:15:7: error: empty character constant
 ans = ''
       ^