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
Ashwin Menon: 2012-09-19 22:15:01

Are the nodes contiguous?

1, 2, 3 ... N?

KEVALSAHU: 2013-12-30 05:22:25

simple problem guys :)

Last edit: 2012-08-26 01:14:34
: 2012-06-21 09:40:19

Last edit: 2014-02-27 08:09:25
Diego Guapo Mendieta: 2012-05-01 18:51:58

give me the solution :D

tracy filbert ridwan: 2011-11-04 06:11:52

just a simple flood fill :D

pavan: 2011-07-22 17:55:06

weak test cases

albertg: 2011-04-24 10:33:39

NO

kiransk: 2011-04-22 04:44:35

is the input graph connected?

albertg: 2011-04-19 07:03:38

YES. THAT'S RIGHT.


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-RHINO
Resource:Co-author Amber