def fib(n):
    n1 = n2 = tmp = 1
    for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
    return tmp

print(fib(int(input()))) def fib(n):
    n1 = n2 = tmp = 1
    for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
    return tmp fib n1 = n2 = tmp = 1 n1 1 = n2 = tmp = 1 n2 1 tmp for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
     _ range(n - 1) range n - 1 n 1 tmp = n1 + n2 tmp n1 + n2 n1 n2 n1, n2 = n2, tmp n1 n2 n2 tmp return tmp tmp n n print(fib(int(input()))) print fib(int(input())) fib int(input()) int input() input def fib(n):
    n1 = n2 = tmp = 1
    for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
    return tmp def fib(n):
    n1 = n2 = tmp = 1
    for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
    return tmp fib
def fib(n):
    n1 = n2 = tmp = 1
    for _ in range(n - 1):
        tmp = n1 + n2
        n1, n2 = n2, tmp
    return tmp

print(fib(int(input())))