Problem:
Score : 200 points

Problem Statement

It is November 18 now in Japan. By the way, 11 and 18 are adjacent Lucas numbers.

You are given an integer N. Find the N-th Lucas number.

Here, the i-th Lucas number L_i is defined as follows:

L_0=2

L_1=1

L_i=L_{i-1}+L_{i-2} (i≥2)

Constraints

1≤N≤86

It is guaranteed that the answer is less than 10^{18}.

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the N-th Lucas number.

Sample Input 1

5

Sample Output 1

11

L_0=2

L_1=1

L_2=L_0+L_1=3

L_3=L_1+L_2=4

L_4=L_2+L_3=7

L_5=L_3+L_4=11

Thus, the 5-th Lucas number is 11.

Sample Input 2

86

Sample Output 2

939587134549734843

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Scanner;

public class Main {
	public static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		//A
		/*int N = sc.nextInt();
		String N_S = String.valueOf(N);
		char N1,N2,N3,N4;
		N1 = N_S.charAt(0);
		N2 = N_S.charAt(1);
		N3 = N_S.charAt(2);
		N4 = N_S.charAt(3);
		if((N1==N2&&N1==N3)||(N2==N4&&N3==N4))
			System.out.println("Yes");
		else
			System.out.println("No");*/

		//B
		int N =sc.nextInt();
		ArrayList<Integer> List = new ArrayList<Integer>();
		List.add(2);
		List.add(1);
		for(int i = 2 ; i <= N ; i++){
			List.add(List.get(i-1)+List.get(i-2));
		}
		System.out.println(List.get(N));
	}
}