How to get first item 100% and rest in 50% i.e in two columns if the total number of list is an odd number

I am working on a blog listing page. There is a condition required:

• If the total number of items is odd then the first item should be in 100% width and the rest in 50%. So that means in two columns.

• If the total number is even then it would be in two columns (50% width each).