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, vN).

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
innovolt: 2014-04-11 13:03:18

gud1 nd easy1 simple dfs

Anubhav Balodhi : 2014-03-29 21:25:37

Easier than I thought... agreed with both the points of @Rastogi..

heatOn: 2014-03-17 11:59:31

No need for BFS or DFS !! easy one .

californiagurl: 2014-03-06 04:51:00

for a given test case can multiple edges exist between two nodes?
is the best method similar to kruskal's MST algo or DFS/BFS?

Last edit: 2014-03-06 16:48:52
hiddenman: 2014-02-13 19:23:19

easy 1..... :)

sonam: 2014-02-02 08:25:13

mai DFS use kar rahi hu to wo to O(2*E) me ho jata hai to phir TLE kyo plz tell me.mai bahut dino se try kar rahi hu

sonam: 2014-02-02 08:22:23

i am using adjecency list and use DFS.
still i m getting TLE.can any one tell me why plzzzzzzzzzzz.

Shubham Sharma: 2014-01-21 16:41:12

Very Weak test cases !

adze: 2014-01-10 23:52:01

@Paul Draper
answer for test case
4 3
1 2
3 4
1 3
is YES, no need to build tree in order

Bhavik: 2013-12-10 15:00:16

kindly check my solution id:10630933
giving WA..don't know why?


Added by:Thanh-Vy Hua
Date:2007-03-28
Time limit:0.5s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO
Resource:Co-author Amber