import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); int n = in.nextInt(); int[] dp = new int[n]; dp[0] = 1; dp[1] = 1; for(int i = 2; i < n; i++){ dp[i] = dp[i - 2] + dp[i - 1]; } System.out.println(dp[n-1]); } }