def main():
    import sys
    A, B = map(int, sys.stdin.readline().split())
    d = A + B
    if d == 0:
        print("1.0000000000000000")
        return
    sum_total = 0.0
    s = 2
    sum_total += 1.0 / (s ** s)
    k = 1
    while True:
        s = 2 + 3 * k
        term = 2.0 / (s ** s)
        sum_total += term
        if term < 1e-20:
            break
        k += 1
    print("{0:.20f}".format(sum_total))

if __name__ == "__main__":
    main()