How to Ensure That the Regular Output Bit Is a One

If all of my input bits, including the carry in bit, are zero, obviously, it should also be zero. If i have exactly one of my inputs being one, then my output should be one. In the case where i have either two or three of the imput its, including the carrying out bit, being a one, you can do that using x or gates,. I won't describe the exact cecretary because it's a little bit confusing to try and explain it without being able to draw a diagram. But it's fairly simple to do. You can do it just with a handful of gates.