using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int n = Convert.ToInt32(Console.ReadLine());
if (n <= 0)
{
Console.WriteLine("必须大于0");
return;
}
if (n == 1) //时刻注意边界值!!!
{
Console.WriteLine("1");
return;
}
int[] data = new int[n];
data[0] = 1;
data[1] = 1;
for (int i = 2; i < n; i++)
{
data[i] = data[i - 1] + data[i - 2];
}
Console.WriteLine(data[n - 1]);
Console.ReadLine();
}
}
}