There are 2 trees at the exotic bird show (Tree "A" and "B")

and on both trees are some exotic birds.

The birds of tree A say to the birds of tree B,

that if one of you comes to our tree, then our population will be double yours.

Then the birds of tree B tell to the birds of tree A

that if one of you comes here, then our population will be equal to that of yours..

How many birds in each tree?