using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp3 {
    class Program {
        static void Main(string[] args) {
            var scanner = new Scanner();
            double P = scanner.NextDouble();
            double Q = scanner.NextDouble();
            double R = scanner.NextDouble();

            double ans = 0;
            ans = Math.Max(ans, (P + Q) / (P + Q + R));
            ans = Math.Max(ans, (Q + R) / (P + Q + R));
            ans = Math.Max(ans, (P + R) / (P + Q + R));
            Console.WriteLine(ans);
            
        }
    }

    class Scanner {
        int index = 0;
        string[] tokens = { };

        public string Next() {
            if (index == tokens.Length) {
                index = 0;
                tokens = Console.ReadLine().Split(' ');
            }
            return tokens[index++];
        }

        public int NextInt() {
            return int.Parse(Next());
        }

        public long NextLong() {
            return long.Parse(Next());
        }

        public double NextDouble() {
            return double.Parse(Next());
        }
    }
}