MAXN = 45
fibs = [-1] * MAXN


def fib(n):
    """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """
    if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

    return fibs[n]


def run():
    n = int(input())
    print(fib(n))


if __name__ == '__main__':
    run()
 MAXN = 45 MAXN 45 fibs = [-1] * MAXN fibs [-1] * MAXN [-1] -1 MAXN def fib(n):
    """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """
    if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

    return fibs[n] fib """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """ if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

     n == 0 n 0 return 1 1 elif n == 1:
        return 1
     n == 1 n 1 return 1 1 elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

     fibs[n] == -1 fibs[n] fibs n -1 fibs[n] = fib(n-1) + fib(n-2) fibs[n] fibs n fib(n-1) + fib(n-2) fib(n-1) fib n-1 n 1 fib(n-2) fib n-2 n 2 return fibs[n] fibs[n] fibs n n n def run():
    n = int(input())
    print(fib(n)) run n = int(input()) n int(input()) int input() input print(fib(n)) print fib(n) fib n if __name__ == '__main__':
    run() __name__ == '__main__' __name__ '__main__' run() run def fib(n):
    """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """
    if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

    return fibs[n] def fib(n):
    """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """
    if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

    return fibs[n] fib MAXN = 45 45 MAXN fibs = [-1] * MAXN [-1] * MAXN fibs def run():
    n = int(input())
    print(fib(n)) def run():
    n = int(input())
    print(fib(n)) run
MAXN = 45
fibs = [-1] * MAXN


def fib(n):
    """Returns n-th fibonacci number

    >>> fib(3)
    3
    >>> fib(10)
    89
    >>> fib(20)
    10946
    """
    if n == 0:
        return 1
    elif n == 1:
        return 1
    elif fibs[n] == -1: 
        fibs[n] = fib(n-1) + fib(n-2)

    return fibs[n]


def run():
    n = int(input())
    print(fib(n))


if __name__ == '__main__':
    run()

