**94 人解决**，117 人已尝试。

**113 份提交通过**，共有 491 份提交。

**3.6** EMB 奖励。

**单点时限: **2.0 sec

**内存限制: **256 MB

Someone has let a goat in a square kitchen-garden and had bound it to a stake. The stake is driven into the ground in the very midst of the square. The goat is hungry as a hunter and very voracious, and eats everything that can be reached without leaving the square and tearing the roap. What area of the kitchen-garden will be ate round?

There are several test cases.Each contains lengths of the garden sides and a cord length in meters (natural numbers not exceeding $100$, located in one line and separated with a space).

Should contain an area of the kitchen-garden (in square meters to within $3$ symbols after a decimal point), ate round by the goat.

Input

10 6

Output

95.091

**94 人解决**，117 人已尝试。

**113 份提交通过**，共有 491 份提交。

**3.6** EMB 奖励。

**创建**: 13 年，1 月前.

**修改**: 3 年，3 月前.

**最后提交**: 3 周前.

**来源**: The 3rd high school children programming contest, USU, Yekaterin

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