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
    p = sorted([P, Q, R])
    ans = Fraction(max(p[0] + p[1], p[2]), d)
    print(ans.numerator / ans.denominator)


main()