P,C=gets.split.map(&:to_i)
def go(pos, p, limit, num)
    if(pos==limit)
        return num
    end
    ar=nil
    if(pos<p)
        ar = [2,3,5,7,11,13]
    else
        ar = [4,6,8,9,10,12]
    end
    total = 0
    ar.map{|i|
        total += go(pos+1, p, limit, num*i)
    }
    return total
end
puts 1.0 * go(0, P, P+C, 1) / (6**(P+C) * 1.0)