using System;
using System.Collections.Generic;
using static System.Console;
namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] N = ReadLine().Split(' ');
            long X = long.Parse(N[0]);
            long Y = long.Parse(N[1]);
            long Z = long.Parse(N[2]);

            if(X > Z)
            {
                WriteLine(0);
            }
            else if(X <= Z && Y > Z || Y <= Z && X > Z || X == Y)
            {
                WriteLine(Z - 1);
            }
            else
            {
                WriteLine(Z - 2);
            }
        }
    }
}