# -*- coding: utf-8 -*-
 
 
def main(n):
    lst = [1, 1]
    for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
    return lst[n]
 

if __name__ == '__main__': 
    n = int(input())
    print(main(n)) def main(n):
    lst = [1, 1]
    for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
    return lst[n]
  main lst = [1, 1] lst [1, 1] 1 1 for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
     i range(2, n + 1) range 2 n + 1 n 1 lst.append(lst[i - 2] + lst[i - 1]) lst.append lst append lst[i - 2] + lst[i - 1] lst[i - 2] lst i - 2 i 2 lst[i - 1] lst i - 1 i 1 return lst[n] lst[n] lst n n n if __name__ == '__main__': 
    n = int(input())
    print(main(n)) __name__ == '__main__' __name__ '__main__' n = int(input()) n int(input()) int input() input print(main(n)) print main(n) main n def main(n):
    lst = [1, 1]
    for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
    return lst[n]
  def main(n):
    lst = [1, 1]
    for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
    return lst[n]
  main n = int(input()) int(input()) n
# -*- coding: utf-8 -*-
 
 
def main(n):
    lst = [1, 1]
    for i in range(2, n + 1):
        lst.append(lst[i - 2] + lst[i - 1])
    return lst[n]
 

if __name__ == '__main__': 
    n = int(input())
    print(main(n))