If you can't remember which character corresponds to which rule, remember that "輪" contains a loop, and "切" doesn't!

                                                                                                                                                --- Lavaloid

Grammy is a puzzle master. Today, she is playing a variant of "Wagiri" puzzle.

The puzzle consists of a simple connected graph with vertices with some Chinese characters on it. Each edge has a "Lun" or "Qie" symbol on it.

The goal is to delete some of the edges to form a connected subgraph (including all of the vertices) such that:

•  Each remaining edge with the character ``Lun'' on it must be on at least one cycle formed by the remaining edges.
•  Each remaining edge with the character ``Qie'' on it must not be on any cycle formed by the remaining edges.

For example, the picture on the left illustrates an unsolved puzzle, and the picture on the right shows a solution to the puzzle, in which the highlighted edges are chosen in the final subgraph.

Grammy wants to find a solution to the puzzle. Please help Grammy find a solution, or report that no solution exists.

输入描述:

The first line contains  integers  (), denoting the number of vertices and the number of edges. 

Each of the next  lines contains  integers  () and a string  ("",""), denoting that there is an edge between  and , and the type of this edge is . 

It is guaranteed that the given graph is a simple connected graph, that is, there are no self-loops or multiple edges, and all vertices are directly or indirectly connected by edges.

输出描述:

If the solution does not exist, output "" on a single line.

Otherwise, output "" on the first line, then output a single integer  () on the second line, followed by  lines, each of which contains two integers , denoting a remaining edge in your solution. If there are multiple solutions, output any.

4 5
1 2 Lun
1 3 Lun
1 4 Qie
2 3 Lun
3 4 Qie

YES
4
1 2
1 3
2 3
1 4

4 5
1 2 Lun
1 3 Qie
1 4 Qie
2 3 Lun
3 4 Qie

NO