# Red Blue Graph

BUET Inter University Pro...
Limits 4s, 512 MB

You are given a connected, undirected, unweighted graph. You need to assign one of the two colors Red or Blue to every edge of the graph in such a way that, for each node $|degree_R-degree_B| \leq 1$.
$degree_R$ of a node is the number of adjacent edges to that node which are colored Red.
$degree_B$ of a node is the number of adjacent edges to that node which are colored Blue.




## Input

The first line contains one integer $T$ - the number of test cases. First line of each testcase contains two integers $N$, $M$ - the number of vertices and the number of edges in the graph respectively. Each of the next $M$ lines contain two integers $u_i$ and $v_i$ describing an undirected edge in the graph.

$1 \leq T \leq 100$
$1 \leq N \leq 10^5$
$N-1 \leq M \leq min(3*10^5, (N*(N-1))/2)$
Sum of $N$ over all testcases doesn’t exceed $10^6$ and sum of $M$ over all testcases also doesn’t exceed $10^6$.
It is guaranteed that the graph is connected, it has no self-loop and there is at most one edge between every pair of vertices.

## Output

If it is not possible to find such a coloring, print $-1$. Otherwise print one such coloring of the edges in the order given. If there exists more than one coloring you can print any one. You should print a string containing only $R$ and $B$ to denote the coloring.

## Sample

InputOutput
2
6 5
1 2
1 3
2 4
2 5
5 6
3 3
1 2
2 3
1 3

BRRRB
-1