CF77B.Falling Anvils

For some reason in many American cartoons anvils fall from time to time onto heroes' heads. Of course, safes, wardrobes, cruisers, planes fall sometimes too... But anvils do so most of all.

Anvils come in different sizes and shapes. Quite often they get the hero stuck deep in the ground. But have you ever thought who throws anvils from the sky? From what height? We are sure that such questions have never troubled you!

It turns out that throwing an anvil properly is not an easy task at all. Let's describe one of the most popular anvil throwing models.

Let the height p of the potential victim vary in the range [0;a] and the direction of the wind q vary in the range [ - b;b]. p and q could be any real (floating) numbers. Then we can assume that the anvil will fit the toon's head perfectly only if the following equation has at least one real root:

Determine the probability with which an aim can be successfully hit by an anvil.

You can assume that the p and q coefficients are chosen equiprobably and independently in their ranges.

出于某种原因，在许多美国动画片中，铁砧会不时地从天而降，砸在主角的头上。当然，保险箱、衣柜、巡洋舰、飞机等有时也会掉落……但铁砧掉落的频率最高。

铁砧有各种尺寸和形状。它们常常把主角深深砸进地面。但你是否曾想过：究竟是谁把铁砧从天上扔下来的？从多高的地方扔下来的？我们确信，这类问题从未困扰过你！

事实上，正确地投掷铁砧绝非易事。下面我们来描述一种最流行的铁砧投掷模型。

设潜在受害者的高度 $p$ 在区间 $[0; a]$ 内变化，风向 $q$ 在区间 $[-b; b]$ 内变化。$p$ 和 $q$ 可以是任意实数（即浮点数）。此时我们可以假设：仅当如下方程至少存在一个实根时，铁砧才能精准命中动画角色的头部：

试求铁砧成功命中目标的概率。

你可以假设系数 $p$ 和 $q$ 在各自取值范围内被独立、等概率地选取。

The first line contains integer t (1 ≤ t ≤ 10000) — amount of testcases.

Each of the following t lines contain two space-separated integers a and b (0 ≤ a, b ≤ 106).

Pretests contain all the tests with 0 < a < 10, 0 ≤ b < 10.

第一行包含一个整数 $t$（$1 \leq t \leq 10000$）——测试用例的数量。

接下来的 $t$ 行，每行包含两个以空格分隔的整数 $a$ 和 $b$（$0 \leq a, b \leq 10^6$）。

预测试包含所有满足 $0 < a < 10$ 且 $0 \leq b < 10$ 的测试用例。

Print t lines — the probability of a successful anvil hit for each testcase. The absolute or relative error of the answer should not exceed 10 - 6.

输出 t 行——每个测试用例中铁砧成功击中的概率。答案的绝对或相对误差不得超过 $10^{-6}$。