/in/foo.cc: In function 'int bs(int, int)':
/in/foo.cc:5:6: warning: unused variable 'n' [-Wunused-variable]
  int n = 0, ys, ls = 0 , lsb = b;
      ^
/in/foo.cc:20:22: warning: 'ys' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return (ys*(a/ys)*(b/ys));
                    ~~^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:20:22: warning: 'ys' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return (ys*(a/ys)*(b/ys));
                    ~~^~~~
/in/foo.cc:5:13: note: 'ys' was declared here
  int n = 0, ys, ls = 0 , lsb = b;
             ^~