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Greedy Petya

2000ms 262144K

Description:

Petya is an unexperienced programming contestant. Recently he has come across the following problem:

You are given a non-directed graph which consists of n nodes and m edges. Your task is to determine whether the graph contains a Hamiltonian path.

Petya wrote a quick bug-free code which he believes solves this problem. After that Petya decided to give this problem for April Fools Day contest. Unfortunately, Petya might have made a mistake, and it's quite possible that his algorithm is wrong. But this isn't a good excuse to leave the contest without submitting this problem, is it?

Input:

The first line contains two integers n, m (1 ≤ n ≤ 20; 0 ≤ m ≤ 400). Next m lines contain pairs of integers vi, ui (1 ≤ vi, ui ≤ n).

Output:

Follow the format of Petya's code output.

Sample Input:

2 3
1 2
2 1
1 1

Sample Output:

Yes

Sample Input:

3 0

Sample Output:

No

Sample Input:

10 20
3 10
4 6
4 9
7 5
8 8
3 10
9 7
5 2
9 2
10 6
10 4
1 1
7 2
8 4
7 2
1 8
5 4
10 2
8 5
5 2

Sample Output:

No

Informação

Codeforces

Provedor Codeforces

Código CF290F

Tags

*specialdfs and similargraphsgreedy

Submetido 0

BOUA! 0

Taxa de BOUA's 0%

Datas 09/05/2023 08:43:06

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