/in/foo.c: In function 'F':
/in/foo.c:12:9: warning: 'n' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return n;
         ^
/in/foo.c: In function 'main':
/in/foo.c:23:2: warning: 'n' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d%d",F(b,n1),F(c,n2));
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.c:23:2: warning: 'n' may be used uninitialized in this function [-Wmaybe-uninitialized]