#813. Tribonacci
T₁ = T₂ = T₃ = 1, Tₙ = Tₙ₋₁ + Tₙ₋₂ + Tₙ₋₃. You get n. Find Tₙ.
### Input
One integer n (1 ≤ n ≤ 70).
### Output
A number.
Examples
Input
63
Output
11152435162266241
Input
34
Output
235795681
💡 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.