using System.Collections.Generic;
using System;

public class Hello
{
    static void Main()
    {
        Console.ReadLine();
        var a = new int[3];
        var ok = true;
        for (int i = 0; i < 3; i++)
        {
            string[] line = Console.ReadLine().Trim().Split(' ');
            if (line.Length > 1) { Console.WriteLine("assert"); ok = false; break; }
            a[i] = int.Parse(line[0]);
        }
        if (ok)
        {
            var b = new List<int>();
            b.Add(a[0] + a[1]);
            b.Add(a[1] + a[2]);
            b.Add(a[2] + a[0]);
            b.Sort();
            if (b[1] == b[2]) Console.WriteLine(b[0]);
            else Console.WriteLine(b[1]);
        }
    }
}