/in/foo.cc: In function 'int main()':
/in/foo.cc:10:8: warning: unused variable 'k' [-Wunused-variable]
  int x,k=1;
        ^
/in/foo.cc:11:13: warning: unused variable 'dis' [-Wunused-variable]
  double oil,dis=500;
             ^~~
/in/foo.cc:15:21: warning: 'oil' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%.2lf",oil);
                     ^