Reverse Number

Problem Background

Special for beginners, ^_^

Problem Description

Write a program using a recursive algorithm that reads a non-negative integer and outputs its reverse (digits in reverse order).

Input Format

A non-negative integer.

Output Format

The reversed result.

Sample Input

123

Sample Output

321

Constraints

1s, 1024KiB for each test case.

All recursion splits an original problem that cannot be answered directly into a smaller subproblem of essentially the same nature, until the scale is small enough to be answered directly.

All data fit within int.

Note: the reverse of $100$ is $001$.