#agc027c. [agc027_c]ABland Yard
[agc027_c]ABland Yard
Problem Statement
You are given an undirected graph consisting of vertices and edges. The vertices are numbered to , and the edges are numbered to . In addition, each vertex has a label, A
or B
. The label of Vertex is . Edge bidirectionally connects vertex and .
The phantom thief Nusook likes to choose some vertex as the startpoint and traverse an edge zero or more times. Today, he will make a string after traveling as above, by placing the labels of the visited vertices in the order visited, beginning from the startpoint.
For example, in a graph where Vertex has the label A
and Vertex has the label B
, if Nusook travels along the path $1 \\rightarrow 2 \\rightarrow 1 \\rightarrow 2 \\rightarrow 2$, the resulting string is ABABB
.
Determine if Nusook can make all strings consisting of A
and B
.
Constraints
- is
A
orB
. - The given graph may NOT be simple or connected.
Input
Input is given from Standard Input in the following format:
Output
If Nusook can make all strings consisting of A
and B
, print Yes
; otherwise, print No
.
Sample Input 1
2 3
AB
1 1
1 2
2 2
Sample Output 1
Yes
- Since Nusook can visit Vertex and Vertex in any way he likes, he can make all strings consisting of
A
andB
.
Sample Input 2
4 3
ABAB
1 2
2 3
3 1
Sample Output 2
No
- For example, Nusook cannot make
BB
. - The given graph may not be connected.
Sample Input 3
13 23
ABAAAABBBBAAB
7 1
10 6
1 11
2 10
2 8
2 11
11 12
8 3
7 12
11 2
13 13
11 9
4 1
9 7
9 6
8 13
8 6
4 10
8 7
4 3
2 1
8 12
6 9
Sample Output 3
Yes
Sample Input 4
13 17
BBABBBAABABBA
7 1
7 9
11 12
3 9
11 9
2 1
11 5
12 11
10 8
1 11
1 8
7 7
9 10
8 8
8 12
6 2
13 11
Sample Output 4
No