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);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int n1 = 1, n2 = 1, n = 1;
            for(int i = 1; i <= a; i++) {
                if(i >= 3) {
                    int temp = n2;
                    n2 = n1 + n2;
                    n1 = temp;
                    n = n2;
                }
            }
            System.out.println(n);
        }
    }
}