/in/foo.c: In function 'main':
/in/foo.c:15:7: error: expected expression before 'int'
   15 |     Y(int i,int n);
      |       ^~~
/in/foo.c:15:5: error: too few arguments to function 'Y'
   15 |     Y(int i,int n);
      |     ^
/in/foo.c:2:5: note: declared here
    2 | int Y(int i,int n)
      |     ^