Pairs

Description:

Input:

The first line contains two space-separated integers $$$n$$$ and $$$m$$$ ($$$2 \leq n \leq 300\,000$$$, $$$1 \leq m \leq 300\,000$$$) — the upper bound on the values of integers in the pairs, and the number of given pairs.

The next $$$m$$$ lines contain two integers each, the $$$i$$$-th of them contains two space-separated integers $$$a_i$$$ and $$$b_i$$$ ($$$1 \leq a_i, b_i \leq n, a_i \neq b_i$$$) — the integers in the $$$i$$$-th pair.

Output:

Output "YES" if there exist two integers $$$x$$$ and $$$y$$$ ($$$1 \leq x < y \leq n$$$) such that in each given pair at least one integer is equal to $$$x$$$ or $$$y$$$. Otherwise, print "NO". You can print each letter in any case (upper or lower).

Sample Input:

4 6
1 2
1 3
1 4
2 3
2 4
3 4

Sample Output:

NO

Sample Input:

5 4
1 2
2 3
3 4
4 5

Sample Output:

YES

Sample Input:

300000 5
1 2
1 2
1 2
1 2
1 2

Sample Output:

YES

Note:

In the first example, you can't choose any $$$x$$$, $$$y$$$ because for each such pair you can find a given pair where both numbers are different from chosen integers.

In the second example, you can choose $$$x=2$$$ and $$$y=4$$$.

In the third example, you can choose $$$x=1$$$ and $$$y=2$$$.