CodeForces 624A Save Luke神庙大逃亡（暑期小练习）

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本文介绍了一个关于计算角色在特定条件下能存活最长时间的问题。角色被夹在两个逐渐靠近的压榨机之间，需要根据角色宽度、初始距离及两机器的移动速度，计算角色能生存的最大时间。

A. Save Luke

Description

LukeSkywalker got locked up in a rubbish shredder between two presses. R2D2 isalready working on his rescue, but Luke needs to stay alive as long aspossible. For simplicity we will assume that everything happens on a straightline, the presses are initially at coordinates 0 and L,and they move towards each other with speed v₁ and v₂,respectively. Luke has width d andis able to choose any position between the presses. Luke dies as soon as thedistance between the presses is less than his width. Your task is to determinefor how long Luke can stay alive.

Input

Thefirst line of the input contains four integers d, L, v₁, v₂ (1 ≤ d, L, v₁, v₂ ≤ 10 000, d < L) —Luke's width, the initial position of the second press and the speed of thefirst and second presses, respectively.

Output

Printa single real value — the maximum period of time Luke can stay alive for.Your answer will be considered correct if its absolute or relative error doesnot exceed 10^- 6.

Namely:let's assume that your answer is a,and the answer of the jury is b.The checker program will consider your answer correct, if .

Sample Input

Input

26 2 2

Output

1.00000000000000000000

Input

19 1 2

Output

2.66666666666666650000

Hint

Inthe first sample Luke should stay exactly in the middle of the segment, that isat coordinates [2;4], as the presses movewith the same speed.

Inthe second sample he needs to occupy the position .In this case both presses move to his edges at the same time.

题意：

这英文真是看懂了一点。

就是给定角色的体积和速度，怪物移动的速度，以及两者之间的距离，

问这个角色最多活多久。

代码：

/*=============================AC情况===============================*/
/*题目网址:   */
/*时间： */
/*心得：  */

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define G 100

int main() {
	int d,l,v1,v2;
	double ans;
	while(scanf("%d%d%d%d",&d,&l,&v1,&v2)!=EOF) {
		ans=double(l-d)/(double)(v1+v2);
		printf("%lf\n",ans);
	}
	return 0;
}

/*********************************测试数据*********************************


**************************************************************************/