Leaping Over the Stones (bonus subtask)

Problem description. There are n stones lying in a straight line numbered from 1 to n . You are at stone 1 and your destination is stone n . In each move you can either jump to a stone ahead or 2 stones ahead or 3 stones ahead .You can take any number of moves but you have reach the final detination i.e stone n. Given n you have to answer in how many distinct paths can you take to reach the , f