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22321_Chooseanddivide

2022-5-16 18:21| 发布者: Hocassian| 查看: 20| 评论: 0|原作者: 肇庆学院ACM合集

摘要:

C:\Users\Administrator\Downloads\2019-10-12-10-14-5-89506319518500-Problem List-采集的数据-后羿采集器.html

Pro.ID

22321

Title

Choose and divide

Title链接

http://10.20.2.8/oj/exercise/problem?problem_id=22321

AC

Submit

Ratio

100.00%

时间&空间限制

Time Limit: 1200/400 MS (Java/Others) Memory Limit: 131072/65536 K (Java/Others)

描述

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

         m!
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).

输入

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.

输出

Description

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

         m!
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

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
3.99960

Source

Waterloo local contest 1999

样例输入