CF267C.Berland Traffic

普及/提高-

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题目描述

Berland traffic is very different from traffic in other countries. The capital of Berland consists of nn junctions and mm roads. Each road connects a pair of junctions. There can be multiple roads between a pair of junctions. For each road we know its capacity: value cic_{i} is the maximum number of cars that can drive along a road in any direction per a unit of time. For each road, the cars can drive along it in one of two direction. That it, the cars can't simultaneously move in both directions. A road's traffic is the number of cars that goes along it per a unit of time. For road ( ai,bia_{i},b_{i} ) this value is negative, if the traffic moves from bib_{i} to aia_{i} . A road's traffic can be a non-integer number.

The capital has two special junctions — the entrance to the city (junction 1) and the exit from the city (junction nn ). For all other junctions it is true that the traffic is not lost there. That is, for all junctions except for 1 and nn the incoming traffic sum equals the outgoing traffic sum.

Traffic has an unusual peculiarity in the capital of Berland — for any pair of junctions ( x,yx,y ) the sum of traffics along any path from xx to yy doesn't change depending on the choice of the path. Such sum includes traffic along all roads on the path (possible with the "minus" sign, if the traffic along the road is directed against the direction of the road on the path from xx to yy ).

Your task is to find the largest traffic that can pass trough the city per one unit of time as well as the corresponding traffic for each road.

输入格式

The first line contains a positive integer nn — the number of junctions ( 2<=n<=1002<=n<=100 ). The second line contains integer mm ( 1<=m<=50001<=m<=5000 ) — the number of roads. Next mm lines contain the roads' descriptions. Each road contains a group of three numbers aia_{i} , bib_{i} , cic_{i} , where ai,bia_{i},b_{i} are the numbers of junctions, connected by the given road, and cic_{i} ( 1<=ai,bi<=n1<=a_{i},b_{i}<=n ; aibia_{i}≠b_{i} ; 0<=ci<=100000<=c_{i}<=10000 ) is the largest permissible traffic along this road.

输出格式

In the first line print the required largest traffic across the city. Then print mm lines, on each line print the speed, at which the traffic moves along the corresponding road. If the direction doesn't match the order of the junctions, given in the input, then print the traffic with the minus sign. Print the numbers with accuracy of at least five digits after the decimal point.

If there are many optimal solutions, print any of them.

输入输出样例

  • 输入#1

    2
    3
    1 2 2
    1 2 4
    2 1 1000
    

    输出#1

    6.00000
    2.00000
    2.00000
    -2.00000
    
  • 输入#2

    7
    11
    1 2 7
    1 2 7
    1 3 7
    1 4 7
    2 3 7
    2 5 7
    3 6 7
    4 7 7
    5 4 7
    5 6 7
    6 7 7
    

    输出#2

    13.00000
    2.00000
    2.00000
    3.00000
    6.00000
    1.00000
    3.00000
    4.00000
    7.00000
    1.00000
    2.00000
    6.00000
    
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