CF605E.Intergalaxy Trips

普及/提高-

通过率:0%

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题目描述

The scientists have recently discovered wormholes — objects in space that allow to travel very long distances between galaxies and star systems.

The scientists know that there are nn galaxies within reach. You are in the galaxy number 11 and you need to get to the galaxy number nn . To get from galaxy ii to galaxy jj , you need to fly onto a wormhole (i,j)(i,j) and in exactly one galaxy day you will find yourself in galaxy jj .

Unfortunately, the required wormhole is not always available. Every galaxy day they disappear and appear at random. However, the state of wormholes does not change within one galaxy day. A wormhole from galaxy ii to galaxy jj exists during each galaxy day taken separately with probability pijp_{ij} . You can always find out what wormholes exist at the given moment. At each moment you can either travel to another galaxy through one of wormholes that exist at this moment or you can simply wait for one galaxy day to see which wormholes will lead from your current position at the next day.

Your task is to find the expected value of time needed to travel from galaxy 11 to galaxy nn , if you act in the optimal way. It is guaranteed that this expected value exists.

输入格式

The first line of the input contains a single integer nn ( 1<=n<=10001<=n<=1000 ) — the number of galaxies within reach.

Then follows a matrix of nn rows and nn columns. Each element pijp_{ij} represents the probability that there is a wormhole from galaxy ii to galaxy jj . All the probabilities are given in percents and are integers. It is guaranteed that all the elements on the main diagonal are equal to 100100 .

输出格式

Print a single real value — the expected value of the time needed to travel from galaxy 11 to galaxy nn if one acts in an optimal way. Your answer will be considered correct if its absolute or relative error does not exceed 10610^{-6} .

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

输入输出样例

  • 输入#1

    3
    100 50 50
    0 100 80
    0 0 100
    

    输出#1

    1.750000000000000
    
  • 输入#2

    2
    100 30
    40 100
    

    输出#2

    3.333333333333333
    

说明/提示

In the second sample the wormhole from galaxy 11 to galaxy 22 appears every day with probability equal to 0.30.3 . The expected value of days one needs to wait before this event occurs is .

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