/in/foo.c: In function 'main':
/in/foo.c:8:13: error: 'i' undeclared (first use in this function)
    8 |         for(i=0;i<n;i+++){
      |             ^
/in/foo.c:8:13: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:8:25: error: expected expression before ')' token
    8 |         for(i=0;i<n;i+++){
      |                         ^
/in/foo.c:12:16: error: 'o' undeclared (first use in this function)
   12 |         return o;
      |                ^