题目描述
Problem Statement
Given is a simple undirected graph with N vertices and M edges. The vertices are numbered $1, \cdots, N$, and the i-th edge connects Vertices a_i and b_i.
Also given is a sequence of positive integers: $c_1, c_2, \cdots, c_N$.
Convert this graph into a directed graph that satisfies the condition below, that is, for each i, delete the undirected edge (a_i, b_i) and add one of the two direted edges $a_i \to$ b_i and $b_i \to$ a_i.
- For every $i = 1, 2, \cdots, N,$ there are exactly c_i vertices reachable from Vertex i (by traversing some number of directed edges), including Vertex i itself.
In this problem, it is guaranteed that the given input always has a solution.
Input
Input is given from Standard Input in the following format:
N M
a_1 b_1
:
a_M b_M
c_1 c_2 ... c_N
Output
Print M lines.
To add the edge $a_i \to$ b_i for the i-th edge, print -> in the i-th line; to add the edge $b_i \to$ a_i for the i-th edge, print <-.
If there are multiple solutions, any of them will be accepted.
Constraints
- $1 \leq N \leq 100$
- $0 \leq M \leq \frac{N(N - 1)}{2}$
- $1 \leq a_i, b_i \leq N$
- The given graph has no self-loops and no multi-edges.
- $1 \leq c_i \leq N$
- There always exists a valid solution.
Sample Input 1
3 3
1 2
2 3
3 1
3 3 3
Sample Output 1
->
->
->
In a cycle of length 3, you can reach every vertex from any vertex.
Sample Input 2
3 2
1 2
2 3
1 2 3
Sample Output 2
<-
<-
Sample Input 3
6 3
1 2
4 3
5 6
1 2 1 2 2 1
Sample Output 3
<-
->
->
The graph may be disconnected.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分