/in/foo.c: In function 'main':
/in/foo.c:5:5: error: 'input' undeclared (first use in this function)
     input{a,b}
     ^~~~~
/in/foo.c:5:5: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:5:10: error: expected ';' before '{' token
     input{a,b}
          ^