If statements or conditional formatting

Dear Community.

i am not sure if this can be done easily.

In column A I would like to enter either 1, 2 or 3 based on

If a cell in column B is green then the corresponding row column A will be 1

If a cell in column C is green then the corresponding row in column A will be 2

If a cell in column D is green then the corresponding row in column A will be 3

I have manually highlighted the green.

Please let me know if it can be done and how?

Thanks