import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    N = int(readline())
    dp = [0] * 47
    dp[0] = 1
    dp[1] = 1
    for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[N])



if __name__ == '__main__':
    main()

 import sys sys read = sys.stdin.read read sys.stdin.read sys.stdin sys stdin read readline = sys.stdin.buffer.readline readline sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline sys.setrecursionlimit(10 ** 8) sys.setrecursionlimit sys setrecursionlimit 10 ** 8 10 8 INF = float('inf') INF float('inf') float 'inf' MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 def main():
    N = int(readline())
    dp = [0] * 47
    dp[0] = 1
    dp[1] = 1
    for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[N]) main N = int(readline()) N int(readline()) int readline() readline dp = [0] * 47 dp [0] * 47 [0] 0 47 dp[0] = 1 dp[0] dp 0 1 dp[1] = 1 dp[1] dp 1 1 for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
     i range(2,N+1) range 2 N+1 N 1 dp[i] = dp[i-1] + dp[i-2] dp[i] dp i dp[i-1] + dp[i-2] dp[i-1] dp i-1 i 1 dp[i-2] dp i-2 i 2 print(dp[N]) print dp[N] dp N if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    N = int(readline())
    dp = [0] * 47
    dp[0] = 1
    dp[1] = 1
    for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[N]) def main():
    N = int(readline())
    dp = [0] * 47
    dp[0] = 1
    dp[1] = 1
    for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[N]) main read = sys.stdin.read sys.stdin.read read MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD INF = float('inf') float('inf') INF readline = sys.stdin.buffer.readline sys.stdin.buffer.readline readline
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    N = int(readline())
    dp = [0] * 47
    dp[0] = 1
    dp[1] = 1
    for i in range(2,N+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[N])



if __name__ == '__main__':
    main()


