def fibo(n):
	S=[1,1]
	s=1
	if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	return s

def main():
	if __name__=="__main__":
		n=input()
		print(fibo(n))

main() def fibo(n):
	S=[1,1]
	s=1
	if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	return s fibo S=[1,1] S [1,1] 1 1 s=1 s 1 if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	 n>1 n 1 for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	 i range(2,n+1) range 2 n+1 n 1 S.append(S[i-1]+S[i-2]) S.append S append S[i-1]+S[i-2] S[i-1] S i-1 i 1 S[i-2] S i-2 i 2 s=S[i] s S[i] S i return s s n n def main():
	if __name__=="__main__":
		n=input()
		print(fibo(n)) main if __name__=="__main__":
		n=input()
		print(fibo(n)) __name__=="__main__" __name__ "__main__" n=input() n input() input print(fibo(n)) print fibo(n) fibo n main() main def main():
	if __name__=="__main__":
		n=input()
		print(fibo(n)) def main():
	if __name__=="__main__":
		n=input()
		print(fibo(n)) main def fibo(n):
	S=[1,1]
	s=1
	if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	return s def fibo(n):
	S=[1,1]
	s=1
	if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	return s fibo
def fibo(n):
	S=[1,1]
	s=1
	if n>1:
		for i in range(2,n+1):
			S.append(S[i-1]+S[i-2])
			s=S[i]
	return s

def main():
	if __name__=="__main__":
		n=input()
		print(fibo(n))

main()