mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    ans = 0
    p, q, r = map(int, input().split())
    s = p+q+r
    for _ in range(3):
        p, q, r = q, r, p
        ans_stay = p / s
        ans_change = (q+r) / s
        ans = max(ans, ans_stay, ans_change)
    print(ans)


if __name__ == '__main__':
    main()