There is a one person who have two numbers, he tells sum to the person A and product of those numbers to B.

Now there is this conversion between A and B.

A: I don't know what are the numbers.

B: I also don't know what are the numbers.

A: Now i know what are the numbers.

B: Now i also know what are the numbers.

Assuming A and B to be very wise and good in mathematics, What are those two numbers?