from math import log
if __name__ == "__main__":
    p_data = [int(i) for i in input().split()]
    q_data = [int(i) for i in input().split()]
    p_total = len(p_data) + 1e-5
    q_total = len(q_data) + 1e-5
    x_unique = []
    for x in p_data + q_data:
        if x not in x_unique:
            x_unique.append(x)
    p_stat = {x: 0 for x in x_unique}
    q_stat = {x: 0 for x in x_unique}
    for x in p_data:
        p_stat[x] += 1
    for x in q_data:
        q_stat[x] += 1
    kl_val = 0
    for x in x_unique:
        p_proba = p_stat[x] / p_total + 1e-5
        q_proba = q_stat[x] / q_total + 1e-5
        kl_val += p_proba * log(p_proba / q_proba, 2)
    print("%.2f" % kl_val)