def f(n):
    a, b=1, 1
    for i in range(n):
        a, b=a+b, a
    return b
print(f(int(input()))) def f(n):
    a, b=1, 1
    for i in range(n):
        a, b=a+b, a
    return b f a, b=1, 1 a 1 b 1 for i in range(n):
        a, b=a+b, a
     i range(n) range n a, b=a+b, a a a+b a b b a return b b n n print(f(int(input()))) print f(int(input())) f int(input()) int input() input def f(n):
    a, b=1, 1
    for i in range(n):
        a, b=a+b, a
    return b def f(n):
    a, b=1, 1
    for i in range(n):
        a, b=a+b, a
    return b f
def f(n):
    a, b=1, 1
    for i in range(n):
        a, b=a+b, a
    return b
print(f(int(input())))