A man (X) bought a product worth Rs 100 from the Shopkeeper (Y). He paid him through a 500 Rs Note. Realizing that he did not have change, the shopkeeper Y got change for that note from another shopkeeper (Z) and paid Rs 400 to the man.

After a few days, Z realized that the note is fake, And this railed at Y and took 500 Rs back from him.

So in this whole process how much money did Y loose in the end?

The Answer is an integer. Just put the number without any decimal places.