Follow Traffic Rules
题目（https://acs.jxnu.edu.cn/problem/CF5D）描述：
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.
输入：
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).
输出：
Print the answer with at least five digits after the decimal point.
样例输入：
1 1
2 1 3
样例输出：
2.500000000000
样例输入：
5 70
200 170 40
样例输出：
8.965874696353
翻译：
大家都知道Berland的首都和Bercouver（奥林匹克基地）之间用一条笔直的路相连。为了提高这条路的交通力，这里只放置了一个红绿灯，限制车辆的最大速度。Berland的红绿灯都很奇怪，因为它只限制它所在点的之前的路段上的车辆的速度。过了这样的红绿灯，车辆可以以任意速度行驶。
Berland的车的平均加速度是a km/h2，最大速度是v km/h。路总长l千米，红绿灯限制速度为w km/h，它被放置在距离Berland的首都d km的地方。车辆在路段的开始处的初速度为0。找到Berland人从Berland的首都到Bercouver的平均最短时间，车辆按速度规则行驶。
车辆可以以任意速度进入Bercouver。
输入：
第一行包含两个整数a和v(1?≤?a,?v?≤?10000)。第二行包含三个整数，i、d和w(2?≤?l?≤?10000; 1?≤?d?<?l; 1?≤?w?≤?10000)。
输出：
输出小数点后至少保留5为小数的答案。
样例输入：
1 1
2 1 3
样例输出：
2.500000000000
样例输入：
5 70
200 170 40
样例输出：
8.965874696353