Choose and Divide

The binomial coefficient $C(m, n)$ is defined as

$$C(m, n) = \frac{m!}{n!,(m-n)!}$$

Given four natural numbers $p$, $q$, $r$, and $s$, compute the value of $C(p, q)$ divided by $C(r, s)$.

The input consists of a sequence of lines. Each line contains four non-negative integers $p$, $q$, $r$, and $s$, in this order, separated by single spaces. Every integer is smaller than $10{,}000$, and it is guaranteed that $p \ge q$ and $r \ge s$. Read until the end of input.

For each input line, print the value of $C(p, q) / C(r, s)$ on its own line, rounded to exactly $5$ digits after the decimal point (round half up). You may assume the result is never greater than $100{,}000{,}000$.