Recently Manu visited the byteland. He was amazed with lots of different varieties of bytes he encountered there. Seeing this, he thought of a problem: Given an integer n, find out total possible bit string (either 0 or 1) of length n which don't have two contiguous zeroes in them. For example if n = 3, then total possible bit strings are 5 {010, 011, 101, 110, 111}. Now Manu started solving the problem but got busy with some important deployments. He asked you for the help. Please help him figure out the solution