If you just use `sum < x` or `sum < y` rather than both, C compilers do reliably perform that optimization. (You don't need both; `sum < x` and `sum < y` are a

If you just use `sum < x` or `sum < y` rather than both, C compilers do reliably perform that optimization. (You don't need both; `sum < x` and `sum < y` are always both false or both true.)