/in/foo.c: In function 'main':
/in/foo.c:14:21: error: 'is' undeclared (first use in this function); did you mean 'i'?
   14 |                 if (is shuixianhuashu(i)){
      |                     ^~
      |                     i
/in/foo.c:14:21: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:14:23: error: expected ')' before 'shuixianhuashu'
   14 |                 if (is shuixianhuashu(i)){
      |                    ~  ^~~~~~~~~~~~~~~
      |                       )