/in/foo.cc: In function 'int main()':
/in/foo.cc:11:9: warning: unused variable 'xi' [-Wunused-variable]
  int n, xi, yi, count = 0;
         ^~
/in/foo.cc:11:13: warning: unused variable 'yi' [-Wunused-variable]
  int n, xi, yi, count = 0;
             ^~