using System;
using System.Linq;
using System.Collections.Generic;

public class yukicoder
{
    private static Dictionary<decimal, decimal> Memo;

    public static decimal fib(decimal n)
    {
        Memo = new Dictionary<decimal, decimal>();
        return _fib(n);
    }

    private static decimal _fib(decimal n)
    {
        if (n == 0) return 0;
        if (n == 1) return 1;
        if (!Memo.ContainsKey(n))
        {
            Memo[n] = _fib(n - 2) + _fib(n - 1);
        }

        return Memo[n];
    }

    public static void Main()
    {
        decimal[] foo = Console.ReadLine().Split(' ').Select(x => decimal.Parse(x)).ToArray();
        decimal a = foo[0];
        decimal b = foo[1];
        
        Console.WriteLine(fib(a - 1));
    }
}