PT07Y - Is it a tree


You are given an unweighted, undirected graph. Write a program to check if it's a tree topology.

Input

The first line of the input file contains two integers N and M --- number of nodes and number of edges in the graph (0 < N <= 10000, 0 <= M <= 20000). Next M lines contain M edges of that graph --- Each line contains a pair (u, v) means there is an edge between node u and node v (1 <= u,v <= N).

Output

Print YES if the given graph is a tree, otherwise print NO.

Example

Input:
3 2
1 2
2 3

Output:
YES

hide comments
archit saxena: 2015-11-11 09:42:47

can the name of nodes be fractions

dk619: 2015-11-02 23:21:16

Disjoint set data structures is the best

Last edit: 2015-11-03 14:17:06
dragonemperor: 2015-10-21 12:07:39

Union find got AC. At first I set parent of each node as -1. This got TLE. Setting parent[a]=a worked like a charm

Vaibhav Malik: 2015-10-06 20:54:26

AC in one GO :)

jarvis: 2015-09-28 23:37:35

First graph :) first DFS :) love it <3 after 5 WA
AC

Sarthak Munshi: 2015-09-25 14:29:21

Check :
1) edges=nodes-1
2) graph is connected(kosaraju or simple dfs will do )

[Mayank Pratap]: 2015-09-22 14:16:28

Enjoyed this problem... :)

jyotman94: 2015-09-19 21:03:46

First Graph Problem :) AC

ram: 2015-09-02 08:35:16

Easy ques :)
My first graph problem.
AC in one go. :) :)

tonystark1996: 2015-08-31 15:32:46

Weak Test Cases
4 2
1 2
3 4
Answer is NO
But my code gives YES,still code accepted


Added by:Thanh-Vy Hua
Date:2007-03-28
Time limit:0.166s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS
Resource:Co-author Amber