/in/foo.cc: In function 'int main()':
/in/foo.cc:7:18: warning: variable 'x0' set but not used [-Wunused-but-set-variable]
  int a,b,w,x,y,p,x0,y0;
                  ^~
/in/foo.cc:7:21: warning: variable 'y0' set but not used [-Wunused-but-set-variable]
  int a,b,w,x,y,p,x0,y0;
                     ^~