n,m=gets.split.map &:to_i
g=(0..n).map{[]}
m.times{
  u,v=gets.split.map &:to_i
  g[u]<<v
  g[v]<<u
}
z=(0..n).map{}
g[1].each{|v|z[v]=1}
l=g.map{|h|h.select{|v|z[v]}.take(3)}
puts (0..n).any?{|u|g[u].any?{|v|
  l[u].any?{|w|l[v].any?{|x|
    [1,u,v,w,x].uniq.size>4
  }}
}}?:YES: :NO