Calculate the length of a hailstone sequence starting with n. The hailstone sequence starts at any natural number n (the current number), and the next number is defined as 3n+1 when the current number is odd, or n/2 when n is even, and the stopping condition is always when n = 1. Sample sequences: 8 4 2 1 hailLen(8) -> 4 3 10 5 16 8 4 2 1 hailLen(3) -> 8