/in/foo.cc: In function 'int ask(int, int, int)':
/in/foo.cc:25:6: warning: unused variable 'mid' [-Wunused-variable]
  int mid=(l(i)+r(i))>>1;
      ^~~
/in/foo.cc: In function 'void xiu(int, int, int, int)':
/in/foo.cc:32:6: warning: unused variable 'mid' [-Wunused-variable]
  int mid=(l(i)+r(i))>>1;
      ^~~