using System;
using System.Linq;

public class Program
{
    public static void Main()
    {
        var input = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToList();
        var dif = input[1] - input[0] + 1;
        Console.Write("{0}", (input[2] >= dif) ? dif : input[2]);
        return;
    }
}