Race to 1

题目描述

[problemUrl]: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=117&page=show_problem&problem=2862 [PDF](https://uva.onlinejudge.org/external/117/p11762.pdf) ![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11762/b1ef1b689a23762fedd48e6bac11ed55518ccb60.png)

输入输出格式

输入格式


![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11762/a9e8aa18a999254778b847f800ff15db6efad8e6.png)

输出格式


![](https://cdn.luogu.com.cn/upload/vjudge_pic/UVA11762/2f64db9ff88189d3cfead67b6fe9a973785d0c8c.png)

输入输出样例

输入样例 #1

3
1
3
13

输出样例 #1

Case 1: 0.0000000000
Case 2: 2.0000000000
Case 3: 6.0000000000