import sys

sys.setrecursionlimit(10 ** 7)
input = sys.stdin.readline
f_inf = float('inf')
mod = 10 ** 9 + 7


def resolve():
    n = int(input())
    fib = [0] * (n + 1)
    fib[0], fib[1] = 1, 1
    for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
    print(fib[-1])


if __name__ == '__main__':
    resolve()
 import sys sys sys.setrecursionlimit(10 ** 7) sys.setrecursionlimit sys setrecursionlimit 10 ** 7 10 7 input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline f_inf = float('inf') f_inf float('inf') float 'inf' mod = 10 ** 9 + 7 mod 10 ** 9 + 7 10 ** 9 10 9 7 def resolve():
    n = int(input())
    fib = [0] * (n + 1)
    fib[0], fib[1] = 1, 1
    for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
    print(fib[-1]) resolve n = int(input()) n int(input()) int input() input fib = [0] * (n + 1) fib [0] * (n + 1) [0] 0 n + 1 n 1 fib[0], fib[1] = 1, 1 fib[0] fib 0 1 fib[1] fib 1 1 for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
     i range(2, n + 1) range 2 n + 1 n 1 fib[i] = fib[i - 1] + fib[i - 2] fib[i] fib i fib[i - 1] + fib[i - 2] fib[i - 1] fib i - 1 i 1 fib[i - 2] fib i - 2 i 2 print(fib[-1]) print fib[-1] fib -1 if __name__ == '__main__':
    resolve() __name__ == '__main__' __name__ '__main__' resolve() resolve input = sys.stdin.readline sys.stdin.readline input mod = 10 ** 9 + 7 10 ** 9 + 7 mod f_inf = float('inf') float('inf') f_inf def resolve():
    n = int(input())
    fib = [0] * (n + 1)
    fib[0], fib[1] = 1, 1
    for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
    print(fib[-1]) def resolve():
    n = int(input())
    fib = [0] * (n + 1)
    fib[0], fib[1] = 1, 1
    for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
    print(fib[-1]) resolve
import sys

sys.setrecursionlimit(10 ** 7)
input = sys.stdin.readline
f_inf = float('inf')
mod = 10 ** 9 + 7


def resolve():
    n = int(input())
    fib = [0] * (n + 1)
    fib[0], fib[1] = 1, 1
    for i in range(2, n + 1):
        fib[i] = fib[i - 1] + fib[i - 2]
    print(fib[-1])


if __name__ == '__main__':
    resolve()

