#908. Stairs: steps 1, 3
A staircase has n steps. Each time you can climb 1, 3 steps. How many ways are there to land exactly on the top?
### Input
One integer n (1 ≤ n ≤ 60).
### Output
A number.
Examples
Input
32
Output
125491
Input
20
Output
1278
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.