/in/foo.cc: In function 'int main()':
/in/foo.cc:56:6: warning: unused variable 'ny' [-Wunused-variable]
  int ny,nm,nd;
      ^~
/in/foo.cc:56:9: warning: unused variable 'nm' [-Wunused-variable]
  int ny,nm,nd;
         ^~
/in/foo.cc:56:12: warning: unused variable 'nd' [-Wunused-variable]
  int ny,nm,nd;
            ^~
/in/foo.cc: In function 'int ReturnDay(int, int)':
/in/foo.cc:23:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^