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

namespace foryuki
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] str = Console.ReadLine().Split();
            var x = int.Parse(str[0]);
            var y = int.Parse(str[1]);
            var d = int.Parse(str[2]);

            int ans = d + 1;
            if (d > x)ans = ans - (d - x);
            if (d > y)ans = ans - (d - y);
            if (ans < 0) ans = 0;
            Console.WriteLine(ans);
        }


        static int a(int i)
        {
            return -1;
        }




        //-------------------------------------------------------------

        static int[] ConvertStringArrayToIntArray(string[] array)
        {
            return Array.ConvertAll(array, str => int.Parse(str));
        }

        static List<int> ConvertStringArrayToIntList(string[] str)
        {
            var list = new List<int>();
            foreach (var c in str)
            {
                list.Add(int.Parse(c));
            }
            return list;
        }
    }
}