Factorial

Let $n$ be a non-negative integer. The value $n!$ (read "$n$ factorial") is defined as follows. If $n \le 1$, then $n! = 1$. If $n > 1$, then $n!$ is the product of all integers from $1$ to $n$, that is, $n! = 1 \times 2 \times \cdots \times n$. For example, $4! = 1 \times 2 \times 3 \times 4 = 24$.

Write a program that:

• reads a non-negative integer $n$ from standard input,
• computes the units (ones) digit of $n!$ in its decimal representation,
• prints that result to standard output.

The first and only line of standard input contains a single non-negative integer $n$ ($0 \le n \le 30000$).

On the first and only line, print exactly one digit equal to the units digit of $n!$ in its decimal representation.