P,C=gets.split.map(&:to_i)
dp=[]
dp[0]={}
dp[0][1]=1

(1..P+C).each{|i|
    dp[i]={}
    dp[i-1].each{|j, k|
        ar=nil
        if(i<=P)
            ar = [2,3,5,7,11,13]
        else
            ar = [4,6,8,9,10,12]
        end
        ar.each{|l|
            dp[i][j*l] ||= 0
            dp[i][j*l] += k
        }
    }
}

total=0
dp[P+C].each{|i,j|
    total += i*j
}
# puts "total=#{total}"
puts total*1.0 / (1.0 * 6**(P+C))