import sys

input = sys.stdin.readline


def main():
    n = int(input())

    fib = [1] * 46
    for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

    ans = fib[n]
    print(ans)


if __name__ == "__main__":
    main()
 import sys sys input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline def main():
    n = int(input())

    fib = [1] * 46
    for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

    ans = fib[n]
    print(ans) main n = int(input()) n int(input()) int input() input fib = [1] * 46 fib [1] * 46 [1] 1 46 for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

     i range(2, 46) range 2 46 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 ans = fib[n] ans fib[n] fib n print(ans) print ans if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main input = sys.stdin.readline sys.stdin.readline input def main():
    n = int(input())

    fib = [1] * 46
    for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

    ans = fib[n]
    print(ans) def main():
    n = int(input())

    fib = [1] * 46
    for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

    ans = fib[n]
    print(ans) main
import sys

input = sys.stdin.readline


def main():
    n = int(input())

    fib = [1] * 46
    for i in range(2, 46):
        fib[i] = fib[i - 1] + fib[i - 2]

    ans = fib[n]
    print(ans)


if __name__ == "__main__":
    main()

