PROGRAMMING:One stroke

Xiao Ding is infatuated with a game recently, the legendary "one stroke" game.
So what is a stroke? The following figure, as the name suggests, is a map that can be completed. The most basic requirement of a stroke is that in the process of drawing, the pen can not leave the paper, and the lines drawn by the pen can not be repeated, and finally all the lines are completed.

Although Xiao Ding likes to play this game, sometimes it takes half a day to find the answer. Xiaoding heard that writing a computer program can determine whether it can draw a picture with one stroke, so he hopes that kind and lovely you can help him.
Come and help the weak, poor and helpless little Ding.
###Input format:
The number of nodes n (1 < = n < = 1000, numbered 1-N) and the number of edges m are given; Then line m gives the numbers of the two nodes that have edges.
###Output format:
One stroke graph output y, otherwise output n.
###Input sample 1:
```in
3 2
1 2
2 3
```
###Output sample 1:
```out
Y
```
###Input sample 2:
```in
4 3
1 2
1 3
1 4
```
###Output sample 2:
```out
N
```







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