def Fibonacci(N):
	if N==1 : return 1
	if N==2 : return 1
	return Fibonacci(N-2)+Fibonacci(N-1)
 
x=int(input())
print(Fibonacci(x))
 
				ZGVmIEZpYm9uYWNjaShOKToKCWlmIE49PTEgOiByZXR1cm4gMQoJaWYgTj09MiA6IHJldHVybiAxCglyZXR1cm4gRmlib25hY2NpKE4tMikrRmlib25hY2NpKE4tMSkKCQp4PWludChpbnB1dCgpKQpwcmludChGaWJvbmFjY2koeCkpCg==