# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10 ** 9)
def input(): return sys.stdin.readline().strip()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))

N=INT()

memo=[0]*50
memo[0]=memo[1]=1
def rec(n):
    if memo[n]:
        return memo[n]
    memo[n]=rec(n-1)+rec(n-2)
    return memo[n]

print(rec(N))
 import sys sys sys.setrecursionlimit(10 ** 9) sys.setrecursionlimit sys setrecursionlimit 10 ** 9 10 9 def input(): return sys.stdin.readline().strip() input def INT(): return int(input()) INT def MAP(): return map(int, input().split()) MAP def LIST(): return list(map(int, input().split())) LIST N=INT() N INT() INT memo=[0]*50 memo [0]*50 [0] 0 50 memo[0]=memo[1]=1 memo[0] memo 0 1 =memo[1]=1 memo[1] memo 1 1 def rec(n):
    if memo[n]:
        return memo[n]
    memo[n]=rec(n-1)+rec(n-2)
    return memo[n] rec if memo[n]:
        return memo[n]
     memo[n] memo n return memo[n] memo[n] memo n memo[n]=rec(n-1)+rec(n-2) memo[n] memo n rec(n-1)+rec(n-2) rec(n-1) rec n-1 n 1 rec(n-2) rec n-2 n 2 return memo[n] memo[n] memo n n n print(rec(N)) print rec(N) rec N def LIST(): return list(map(int, input().split())) def LIST(): return list(map(int, input().split())) LIST def INT(): return int(input()) def INT(): return int(input()) INT memo=[0]*50 [0]*50 memo def input(): return sys.stdin.readline().strip() def input(): return sys.stdin.readline().strip() input def MAP(): return map(int, input().split()) def MAP(): return map(int, input().split()) MAP N=INT() INT() N def rec(n):
    if memo[n]:
        return memo[n]
    memo[n]=rec(n-1)+rec(n-2)
    return memo[n] def rec(n):
    if memo[n]:
        return memo[n]
    memo[n]=rec(n-1)+rec(n-2)
    return memo[n] rec
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10 ** 9)
def input(): return sys.stdin.readline().strip()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))

N=INT()

memo=[0]*50
memo[0]=memo[1]=1
def rec(n):
    if memo[n]:
        return memo[n]
    memo[n]=rec(n-1)+rec(n-2)
    return memo[n]

print(rec(N))

