n=int(input())
def func(n):
    fibonacci = [1,2]
    for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
    return fibonacci[n-1]
print(func(n)) n=int(input()) n int(input()) int input() input def func(n):
    fibonacci = [1,2]
    for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
    return fibonacci[n-1] func fibonacci = [1,2] fibonacci [1,2] 1 2 for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
     i range(2,n) range 2 n fibonacci.append(fibonacci[i-2]+fibonacci[i-1]) fibonacci.append fibonacci append fibonacci[i-2]+fibonacci[i-1] fibonacci[i-2] fibonacci i-2 i 2 fibonacci[i-1] fibonacci i-1 i 1 return fibonacci[n-1] fibonacci[n-1] fibonacci n-1 n 1 n n print(func(n)) print func(n) func n def func(n):
    fibonacci = [1,2]
    for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
    return fibonacci[n-1] def func(n):
    fibonacci = [1,2]
    for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
    return fibonacci[n-1] func n=int(input()) int(input()) n
n=int(input())
def func(n):
    fibonacci = [1,2]
    for i in range(2,n):
        fibonacci.append(fibonacci[i-2]+fibonacci[i-1])
    return fibonacci[n-1]
print(func(n))
