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
coding_express: 2013-03-06 19:07:29

please post some inputs

Aayush: 2013-01-11 09:42:15

Last edit: 2013-01-11 09:56:51
Paul Draper: 2012-11-21 03:31:53

Weak test cases. Trees are always built in order; i.e. no
4 3
1 2
3 4
1 3

kailash: 2012-11-14 19:51:05

Can I get some test cases.
My code is working for my inputs but spoj is showing WA.

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


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