因为该题目再提交平台上数据有问题，所以就很不好办，留着以后它数据好了来写一下。

When I was young, my father is a senior gaming enthusiast. One day, we saw a old man in the street .He had a dice and played with other people .Every turn the gambler gives k RMB to the old man and throw the dice . If the point is 1,2 or 3fihe will win 2k RMB back fiotherwise he will get nothing .My father told me, “I can win all his money by the following strategy”.“Each turn I bet on 1 RMB first If I lose I will bet on 2 RMB. If I still lose, I will bet on 4,8,16,...and so on, until I win. And start to bet on 1 RMB, do the same thing again .”“If I don’t have enough money to bet, I will bet on all my money.”Now the question is, if the dice is even, my father has n RMB, the old man has m RMB, they stopuntil one of them lose all his money, what’s the probability of my father’s victory .InputThe input contains multiple test cases.(No more than 20)In each test case:The only line contains two numbers n, m. (0 ≤ n, m ≤ 2000000), indicate my father’s money andthe old man’s . We guarantee max(n, m) ≥ 1.OutputFor each test case, print the answer in five decimal .

Sample Input

1 0

3 3

Sample Output

1.00000

0.50000