using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
 
class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int[] inpt = Reader.GetInt();
        
        int x = inpt[0];
        int y = inpt[1];
        int d = inpt[2];
        int ans = 0;
        if(d > 0) {
            int x1 = 0;
            int y1 = 0;
            int x2 = 0;
            int y2 = 0;
            if(y >= d) {
                x1 = 0;
                y1 = d;
            } else
            {
                y1 = y;
                x1 = d - y;
            }
            if(x >= d) {
                x2 = d;
                y2 = 0;
            } else
            {
                x2 = x;
                y2 = d - x;
            }
            if(x2 >= x1) {
                ans = (x2 - x1) + 1;
            }
        } else
        {
            ans = 1;
        }
        Console.WriteLine(ans);


    }

    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"


1 1 5



 
";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        public static int[] GetInt(char delimiter = ' ', bool trim = false)
        {
            string inptStr = ReadLine();
            if (trim)
            {
                inptStr = inptStr.Trim();
            }
            string[] inpt = inptStr.Split(delimiter);
            int[] ret = new int[inpt.Length];
            for (int i = 0; i < inpt.Length; i++)
            {
                ret[i] = int.Parse(inpt[i]);
            }
            return ret;
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}