from fractions import Fraction
from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    P, Q, R = map(int, input().split())

    d = P + Q + R
    p1 = max(P, Q, R)
    p2 = sum([P, Q, R]) - p1
    ans = Fraction(max(p1, p2), d)
    print(ans.numerator / ans.denominator)


main()