Background

Special for beginners, ^_^

Description

楼梯有N级台阶，上楼可以一步上一阶，也可以一步上二阶。编一递归程序，计算共有多少种不同走法？

Format

Input

Two integers x and y, satisfying $0\leq x,y\leq 32767$ .

Output

One integer, the sum of x and y.

Samples

3

3

Limitation

1s, 1024KiB for each test case.