Recursive Factorial

Background

Congcong has recently been learning about the concept of factorials in mathematics. He wants to know how to calculate the factorial of a number using programming, specifically requiring a recursive approach.

Problem Description

Given an integer $n$ of $1$ or more, return the factorial of $n$, which is $n \times (n-1) \times (n-2) \times \dots \times 1$. Compute the result recursively (without loops).

Input Format

Input is given from standard input in the following format.

An integer $n$.

Output Format

Output is printed to standard output in the following format.

The factorial of $n$.

Sample

1

1

2

2

3

6

Constraints

Time limit: 1 second, Memory limit: 1024KB for each test case.