n=gets.to_i
k=gets.to_i
t=[1.quo(1)]
n.times{
  t=(1..6).map{|i|(t.map{|j|j/6}+[0]*6).rotate(-i)}.inject{|a,b|a.zip(b).map{|i,j|i+j}}
}

u=[1.quo(1)]
(n-k).times{
  u=(1..6).map{|i|(u.map{|j|j/6}+[0]*6).rotate(-i)}.inject{|a,b|a.zip(b).map{|i,j|i+j}}
}
k.times{
  u=(4..6).map{|i|(u.map{|j|j/3}+[0]*6).rotate(-i)}.inject{|a,b|a.zip(b).map{|i,j|i+j}}
}
v=0
t.map!{|i|v+=i;v-i}
p t.zip(u).map{|i,j|i*j}.inject(:+).to_f