How many push-ups can you do?

I literally cannot do any full push-ups I used to like when I did sports in high school, but now I can't so I'm trying to build back up to it. I literally only do like the push-ups with like one knee on the ground.

I cannot do any push-ups at all my arms and my back it's just so weak right now I have to go back in shape so I'm able to do it