CF5D.Follow Traffic Rules

Everybody knows that the capital of Berland is connected to Bercouver (the Olympic capital) by a direct road. To improve the road's traffic capacity, there was placed just one traffic sign, limiting the maximum speed. Traffic signs in Berland are a bit peculiar, because they limit the speed only at that point on the road where they are placed. Right after passing the sign it is allowed to drive at any speed.

It is known that the car of an average Berland citizen has the acceleration (deceleration) speed of a km/h2, and has maximum speed of v km/h. The road has the length of l km, and the speed sign, limiting the speed to w km/h, is placed d km (1 ≤ d < l) away from the capital of Berland. The car has a zero speed at the beginning of the journey. Find the minimum time that an average Berland citizen will need to get from the capital to Bercouver, if he drives at the optimal speed.

The car can enter Bercouver at any speed.

众所周知，贝兰德首都与贝尔库弗（奥运首都）之间由一条直达公路相连。为了提升该公路的通行能力，公路上仅设置了一个限速交通标志。贝兰德的交通标志略显特殊：它仅在标志所处的公路位置起限速作用；车辆刚驶过该标志后，即可任意加速。

已知一位普通贝兰德市民所驾驶汽车的加速度（减速度）为 $a$ km/h²，最大速度为 $v$ km/h。该公路全长 $l$ km，限速标志设于距贝兰德首都 $d$ km 处（满足 $1 \le d < l$），将车速限制为 $w$ km/h。汽车从旅程起点（首都）出发时初速度为 0。若驾驶员以最优速度行驶，求其从首都抵达贝尔库弗所需的最短时间。

汽车可以以任意速度进入贝尔库弗。

The first line of the input file contains two integer numbers a and v (1 ≤ a, v ≤ 10000). The second line contains three integer numbers l, d and w (2 ≤ l ≤ 10000; 1 ≤ d < l; 1 ≤ w ≤ 10000).

输入文件的第一行包含两个整数 $a$ 和 $v$（$1 \le a,\,v \le 10000$）。第二行包含三个整数 $l$、$d$ 和 $w$（$2 \le l \le 10000$；$1 \le d < l$；$1 \le w \le 10000$）。

Print the answer with at least five digits after the decimal point.

答案需保留至少五位小数。