foo.cc: In function ‘int main()’:
foo.cc:16:4: warning: unused variable ‘k’ [-Wunused-variable]
   16 | ll k, m, x, y, l, r, ans = 0;
      |    ^
foo.cc:16:7: warning: unused variable ‘m’ [-Wunused-variable]
   16 | ll k, m, x, y, l, r, ans = 0;
      |       ^
foo.cc:16:16: warning: unused variable ‘l’ [-Wunused-variable]
   16 | ll k, m, x, y, l, r, ans = 0;
      |                ^
foo.cc:16:19: warning: unused variable ‘r’ [-Wunused-variable]
   16 | ll k, m, x, y, l, r, ans = 0;
      |                   ^