/in/foo.c:1:1: error: unknown type name 'def'
 def fun(n):
 ^~~
/in/foo.c: In function 'fun':
/in/foo.c:1:11: error: expected declaration specifiers before ':' token
 def fun(n):
           ^
/in/foo.c:1:5: warning: type of 'n' defaults to 'int' [-Wimplicit-int]
 def fun(n):
     ^~~
/in/foo.c:13:2: warning: control reaches end of non-void function [-Wreturn-type]
  print("no")
  ^~~~~