import sys
input = sys.stdin.readline

m = [1, 1] + [None]*50

def fibonacci(n):
    if m[n-2]:
        pass
    else:
        fibonacci(n-2)
    if m[n-1]:
        pass
    else:
        fibonacci(n-1)

    m[n] = m[n-1] + m[n-2]

N = int(input())

fibonacci(44)
print(m[N])

 import sys sys input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline m = [1, 1] + [None]*50 m [1, 1] + [None]*50 [1, 1] 1 1 [None]*50 [None] None 50 def fibonacci(n):
    if m[n-2]:
        pass
    else:
        fibonacci(n-2)
    if m[n-1]:
        pass
    else:
        fibonacci(n-1)

    m[n] = m[n-1] + m[n-2] fibonacci if m[n-2]:
        pass
    else:
        fibonacci(n-2)
     m[n-2] m n-2 n 2 fibonacci(n-2) fibonacci n-2 n 2 if m[n-1]:
        pass
    else:
        fibonacci(n-1)

     m[n-1] m n-1 n 1 fibonacci(n-1) fibonacci n-1 n 1 m[n] = m[n-1] + m[n-2] m[n] m n m[n-1] + m[n-2] m[n-1] m n-1 n 1 m[n-2] m n-2 n 2 n n N = int(input()) N int(input()) int input() input fibonacci(44) fibonacci 44 print(m[N]) print m[N] m N N = int(input()) int(input()) N input = sys.stdin.readline sys.stdin.readline input def fibonacci(n):
    if m[n-2]:
        pass
    else:
        fibonacci(n-2)
    if m[n-1]:
        pass
    else:
        fibonacci(n-1)

    m[n] = m[n-1] + m[n-2] def fibonacci(n):
    if m[n-2]:
        pass
    else:
        fibonacci(n-2)
    if m[n-1]:
        pass
    else:
        fibonacci(n-1)

    m[n] = m[n-1] + m[n-2] fibonacci m = [1, 1] + [None]*50 [1, 1] + [None]*50 m
import sys
input = sys.stdin.readline

m = [1, 1] + [None]*50

def fibonacci(n):
    if m[n-2]:
        pass
    else:
        fibonacci(n-2)
    if m[n-1]:
        pass
    else:
        fibonacci(n-1)

    m[n] = m[n-1] + m[n-2]

N = int(input())

fibonacci(44)
print(m[N])


