The dragon and the princess are arguing about what to do on the New Year's Eve. The dragon suggests flying to the mountains to watch fairies dancing in the moonlight, while the princess thinks they should just go to bed early. They are desperate to come to an amicable agreement, so they decide to leave this up to chance.

They take turns drawing a mouse from a bag which initially contains *w* white and *b* black mice. The person who is the first to draw a white mouse wins. After each mouse drawn by the dragon the rest of mice in the bag panic, and one of them jumps out of the bag itself (the princess draws her mice carefully and doesn't scare other mice). Princess draws first. What is the probability of the princess winning?

If there are no more mice in the bag and nobody has drawn a white mouse, the dragon wins. Mice which jump out of the bag themselves are not considered to be drawn (do not define the winner). Once a mouse has left the bag, it never returns to it. Every mouse is drawn from the bag with the same probability as every other one, and every mouse jumps out of the bag with the same probability as every other one.
The only line of input data contains two integers *w* and *b* (0 ≤ *w*, *b* ≤ 1000).
1 3
0.500000000
5 5
0.658730159
100 100
0.666295063
100 1
0.990099010
1 100
0.336633663
67 420
0.536897227
0 1000
0.000000000
1000 0
1.000000000
0 0
0.000000000
1000 1000
0.666629617
32 1000
0.507870202
581 406
0.708455368
459 52
0.907503322
900 853
0.672635039
778 218
0.820333392
219 20
0.922525319
815 665
0.689921745
773 467
0.726347987
215 269
0.642626672
93 633
0.534192877
267 270
0.665290172
226 72
0.805082561
666 436
0.716435071
544 519
0.671862905
141 883
0.536951107
581 685
0.648844385
459 487
0.660077510
980 133
0.893190920
858 934
0.657333867
455 299
0.715932720
962 35
0.966054554
840 837
0.667020172
1000 483
0.754259888
958 285
0.813405050
399 649
0.617507391
277 451
0.617396161
155 534
0.563323504
315 898
0.574579114
193 700
0.560544099
713 65
0.922816830
377 720
0.603697168
817 522
0.719439426
695 168
0.836944656
574 969
0.614216493
95 334
0.562182792
691 417
0.726476058
132 781
0.538939829
10 583
0.504240929
888 385
0.767717438
329 31
0.920544382
73 405
0.541293398
513 488
0.672187379
391 852
0.593281183
551 654
0.648141838
429 19
0.959234268
387 102
0.827219303
827 466
0.735005881
705 268
0.783946132
864 70
0.930218970
743 715
0.670910005
50 372
0.531448979
w,b = map(int,input().strip().split())

def solve(w,b):
    if w == 0: return 0
    if b == 0: return 1
    if b == 1: return w/(w+1)
    if b == 2: return ((w*w+w+2)/(w*w+3*w+2)) if w != 1 else 1/3
    
    return w/(w+b) + (b/(w+b))*(((b-1)/(w+b-1)) *    (((b-2)/(w+b-2))*solve(w,b-3) + ((w)/(w+b-2))*solve(w-1,b-2)  ) )
        

print(solve(w,b))
 