@pz,@q = gets.split.map{|e|e.to_f/100.0}

@memo={}
def calc(pi,deep)
    pi = pi<0 ? 0.0 : 1<pi ? 1.0 : pi
    return pi if deep>200 # (´；ω；｀)
    
    return @memo[pi] if @memo[pi]
    r = 0.0
    #unused
    r += (1.0 + calc(pi+@q,deep+1)) /3.0 * (1.0-pi) if pi <1.0
    #used
    r += (1.0 + calc(pi-@q,deep+1)) /2.0 * (pi)  if pi >0.0
    return @memo[pi] = r
end

r = 1.0/3.0 + 1.0/ 3.0 * calc(@pz,0)

p r.to_f