Populating a cell when other cells are populated/not populated

Hi. I was wondering if someone could help me.

I’m trying to populate a cell with the word “Completed” on the condition that 4 other cells are populated (Not Blank).

However, I want this same cell to be populated with “Not Completed” on the condition that 1 or more of the 4 cells, previously mentioned, are not populated (Blank).

If anyone knows how to do this, please let me know. Thanks