Codeforces Round 375 (Div. 2)
E
One-Way Reform
Codeforces
2200
原题
← DF →
翻译中…

There are $*n*$ cities and $*m*$ two-way roads in Berland, each road connects two cities. It is known that there is no more than one road connecting each pair of cities, and there is no road which connects the city with itself. It is possible that there is no way to get from one city to some other city using only these roads.

翻译中…

The road minister decided to make a reform in Berland and to orient all roads in the country, i.e. to make each road one-way. The minister wants to maximize the number of cities, for which the number of roads that begins in the city equals to the number of roads that ends in it.

翻译中…

Input

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The first line contains a positive integer $*t*$ ($1 ≤ *t* ≤ 200$) — the number of testsets in the input.

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Each of the testsets is given in the following way. The first line contains two integers $*n*$ and $*m*$ ($1 ≤ *n* ≤ 200$, $0 ≤ *m* ≤ *n*·(*n* - 1) / 2$) — the number of cities and the number of roads in Berland.

翻译中…

The next $*m*$ lines contain the description of roads in Berland. Each line contains two integers $*u*$ and $*v*$ ($1 ≤ *u*, *v* ≤ *n*$) — the cities the corresponding road connects. It's guaranteed that there are no self-loops and multiple roads. It is possible that there is no way along roads between a pair of cities.

翻译中…

It is guaranteed that the total number of cities in all testset of input data doesn't exceed $200$.

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Pay attention that for hacks, you can only use tests consisting of one testset, so $*t*$ should be equal to one.

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Output

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For each testset print the maximum number of such cities that the number of roads that begins in the city, is equal to the number of roads that ends in it.

翻译中…

In the next $*m*$ lines print oriented roads. First print the number of the city where the road begins and then the number of the city where the road ends. If there are several answers, print any of them. It is allowed to print roads in each test in arbitrary order. Each road should be printed exactly once.

翻译中…

样例

Input #1
2
5 5
2 1
4 5
2 3
1 3
3 5
7 2
3 7
4 2
Output #1
3
1 3
3 5
5 4
3 2
2 1
3
2 4
3 7
InputCopy OutputCopy
题目信息
题号
723E
时间限制
2 s
内存限制
256 MB
标签
构造
DFS 及类似
网络流
图论
贪心

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。