P,C=map(int,input().split())

X=[2,3,5,7,11,13]
Y=[4,6,8,9,10,12]

from itertools import product
L=list(product(range(6),repeat=P+C))

ANS=0
for l in L:
    sc=1
    for i in range(P+C):

        if i<P:
            sc*=X[l[i]]
        else:
            sc*=Y[l[i]]
    ANS+=sc

print(ANS/len(L))