Celebrations

Holi is nearing and brothers Avinash and Abhilash want to celebrate it in a grand manner. They make a decision to order 3 different kinds of paintballs: red, green and blue and then store them in different boxes. They store these paint-balls in $N$ boxes and ensure that there is only one type of paint-ball in each one of them. To be precise, $i^{th}$ box either contains red paint-balls or bl