/in/foo.c: In function 'main':
/in/foo.c:8:2: warning: implicit declaration of function 'Output' [-Wimplicit-function-declaration]
  Output(a,n);
  ^~~~~~
/in/foo.c: In function 'Output':
/in/foo.c:16:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^