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