import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner stdin = new Scanner(System.in); int n = stdin.nextInt(); int[] dp = new int[n + 2]; dp[0] = 1; for (int i = 0; i < n; i++) { dp[i + 1] += dp[i]; dp[i + 2] += dp[i]; } System.out.println(dp[n]); } }