climb

import sys


# Input: n is an int of how many climbing holds there are
# Output: return an integer of how many distinct ways there are to reach the last hold (order matters)
def distinct_ways(n):
    def fib(m):
        if m <= 1:
            return m
        return fib(m - 1) + fib(m - 2)

    def countWays(s):
        return fib(s + 1)

    return countWays(n)


def main():

    # read number of holds
    n = int(input())

    # get the result from your call to distinct_ways()
    result = distinct_ways(n)

    # print the result to standard output
    print(result)


if __name__ == "__main__":
    main()