CF82E.Corridor

普及/提高-

通过率:0%

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题目描述

The first line of the input file contains three integers nn , hh and ff ( 1<=n<=5001<=n<=500 , 1<=h<=101<=h<=10 , h<f<=1000 ). Next, nn lines contain two integers each lil_{i} , rir_{i} ( -5000<=l_{i}<r_{i}<=5000 ), each entry indicates two segments. Endpoints of the first segment are (li,h)(l_{i},h) - (ri,h)(r_{i},h) , and endpoints of the second segment are (li,h)(l_{i},-h) - (ri,h)(r_{i},-h) . These segments describe location of windows. Numbers in the lines are space-separated. It is guaranteed that no two distinct segments have common points.

输入格式

Print the single real number — the area of the illuminated part of the floor with an absolute or relative error of no more than 10410^{-4} .

输出格式

The second sample test is shown on the figure. Green area is the desired area of the illuminated part of the floor. Violet segments indicate windows.

输入输出样例

  • 输入#1

    1 1 2
    -1 1
    

    输出#1

    10.0000000000
    
  • 输入#2

    2 2 4
    -1 0
    1 2
    

    输出#2

    23.3333333333
    

说明/提示

The second sample test is shown on the figure. Green area is the desired area of the illuminated part of the floor. Violet segments indicate windows.

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