@pz,@q = gets.split.map{|e|e.to_f/100}

@memo={}
def calc(pi,deep)
    return 1 if deep>100 # (´；ω；｀)
    
    pi = pi<0 ? 0.0 : 1<pi ? 1.0 : pi
    
    return @memo[pi] if @memo[pi]
    r = 0.0
    #unused
    r += (1-pi) * (1.0/3.0 + 1.0/3.0 * calc(pi+@q,deep+1)) if 1-pi >0
    #used
    r += (pi) * (1.0/2.0 + 1.0/2.0 * calc(pi-@q,deep+1)) if pi >0
    return @memo[pi] = r
end

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

p r.to_f