# Choose and Divide

Time Limit: 1 Second Memory Limit: 32768 KB

The binomial coefficient C(m,n) is defined asm!

C(m,n) = --------

n!(m-n)!

Given four natural numbers p, q, r, and s, compute the the result of dividing C(p,q) by C(r,s).

## Input

Input consists of a sequence of lines. Each line contains four non-negative integer numbers giving values for p, q, r, and s, respectively, separated by a single space. All the numbers will be smaller than 10,000 with p>=q and r>=s.

## Output

For each line of input, print a single line containing a real number with 5 digits of precision in the fraction, giving the number as described above. You may assume the result is not greater than 100,000,000.

## Sample Input

10 5 14 9 93 45 84 59 145 95 143 92 995 487 996 488 2000 1000 1999 999 9998 4999 9996 4998

## Sample Output

0.12587 505606.46055 1.28223 0.48996 2.00000 3.99960Submit

Source: University of Waterloo Local Contest 1999.10.02