n,*k=$<.read.split.map &:to_i
f=->(a,x){
	[*0...a.size].combination(3).send([:any?,:select][x]){|i,j,k|
		a[i]!=a[k]&&((a[i]-a[j])*(a[j]-a[k])<0)&&(b=a.dup;[k,j,i].map{|e|b.delete_at e};!f[b,0])
	}
}
puts (f[k,1][0]||[-1])*' '