using System;
public class Hello{
    public static void Main(){
        
        var balls = Console.ReadLine().Split();
        int red  = int.Parse(balls[0]);
        int blue = int.Parse(balls[1]);
        int white= int.Parse(balls[2]);
        

        while(red!=blue){
            if(white==0)break;
            
            if(red>blue){
                blue++;
                white-=1;
            }
            else{
                red++;
                white-=1;
            }
        }
        
        if(red<blue)
            Console.WriteLine(red + white/2);
        else
            Console.WriteLine(blue + white/2);
            
    }
}