This is a story of four boys - Chinku, Dinku, Pinku and Tinku.

One day all of them decide to save their money in a bank(Joint Account). They select a bank called “Lena Bank”

The bank's specialty is: In every month the money gets doubled.

In 2nd month, Chinku withdraws 100-Rs from bank.
In 3rd month, Dinku withdraws 100-Rs from bank.
In 4th month, Pinku withdraws 100-Rs from bank.

In 5th month, Tinku withdraws 100-Rs from bank.

Then their balance in the bank becomes zero.
How much amount had the boys put in the bank?