#include <stdio.h>
#include <string.h>
#define MAX 110
#define INF 100000000

int graph[MAX][MAX];
bool floyd(int n)
{
	for(int k = 0 ; k < n ; ++k)
	{
		for(int i = 0 ; i < n ; ++i)
		{
			for(int j = 0 ; j < n ; ++j)
			{
				if(graph[i][j]>graph[i][k]+graph[k][j])
				{
					graph[i][j]=graph[i][k]+graph[k][j];
				}
			}
		}
	}
	for(int i = 0 ; i < n ; ++i)
	{
		for(int j = 0 ; j < n ; ++j)
		{
			if(graph[i][j]>7)
			{
				return false ;
			}
		}
		
	}
	return true ;
}

int main()
{
	int m,n;
	while(~scanf("%d%d",&n,&m))
	{
		for(int i = 0 ; i <= n ; ++i)
		{
			for(int j = 0 ; j <= i ; ++j)
			{
				graph[i][j] = graph[j][i] = INF ;
			}
			graph[i][i] = 0 ;
		}
		for(int i = 0 ; i < m ; ++i)
		{
			int x ,y ;
			scanf("%d%d",&x,&y);
			if(x == y)
				continue ;
			graph[x][y] = graph[y][x] = 1 ;
		}
		if(floyd(n))
		{
			puts("Yes");
		}
		else
		{
			puts("No");
		}
	}
	return 0 ;
}