/in/foo.c:1:1: warning: return type defaults to 'int' [-Wimplicit-int]
 input(a)
 ^~~~~
/in/foo.c: In function 'input':
/in/foo.c:2:1: error: expected declaration specifiers before 'b'
 b=a*a
 ^
/in/foo.c:1:1: warning: type of 'a' defaults to 'int' [-Wimplicit-int]
 input(a)
 ^~~~~
/in/foo.c:3:1: warning: control reaches end of non-void function [-Wreturn-type]
 print(b)
 ^~~~~