package demo5;
import java.util.Scanner;
public class JumpFllorTest {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while(sc.hasNext()){
int target = sc.nextInt();
int res = jumpFloor2(target);
System.out.println(res);
}
}
public static int jumpFloor1(int target){
if(target <= 0) return 0;
if(target == 1 || target == 2) return target;
return jumpFloor1(target-1) + jumpFloor1(target-2);
}
public static int jumpFloor2(int target){
if(target <= 0) return 0;
if(target == 1 || target == 2) return target;
int pre1 = 1;
int pre2 = 2;
for (int i = 3; i <= target; i++) {
int cur = pre1 + pre2;
pre1 = pre2;
pre2 = cur;
}
return pre2;
}
}