using System; using System.Linq; using System.Collections.Generic; class Program { static void Main() { int n = ri(); var dp = new long[n + 1]; dp[0] = dp[1] = 1; for(int i = 2; i < n + 1; i++) { dp[i] = dp[i - 1] + dp[i - 2]; } Console.WriteLine(dp[n]); } #region Scan static int ri() { return int.Parse(Console.ReadLine()); } static long rl() { return long.Parse(Console.ReadLine()); } static double rd() { return double.Parse(Console.ReadLine()); } static string rs() { return Console.ReadLine(); } static int[] ria() { return Console.ReadLine().Trim().Split().Select(int.Parse).ToArray(); } static long[] rla() { return Console.ReadLine().Trim().Split().Select(long.Parse).ToArray(); } static double[] rda() { return Console.ReadLine().Trim().Split().Select(double.Parse).ToArray(); } static string[] rsa() { return Console.ReadLine().Trim().Split(); } static void mul(out int a, out int b) { var arr = ria(); a = arr[0]; b = arr[1]; } static void mul(out int a, out int b, out int c) { var arr = ria(); a = arr[0]; b = arr[1]; c = arr[2]; } static void mul(out int a, out int b, out int c, out int d) { var arr = ria(); a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; } static void mul(out long a, out long b) { var arr = rla(); a = arr[0]; b = arr[1]; } static void mul(out long a, out long b, out long c) { var arr = rla(); a = arr[0]; b = arr[1]; c = arr[2]; } static void mul(out long a, out long b, out long c, out long d) { var arr = rla(); a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; } #endregion #region Math const int mod = 1000000007; static bool isprime(long n) { if (n < 2) return false; for (long i = 2; i * i <= n; i++) if (n % i == 0) return false; return true; } #endregion }