# 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

n = int(input())
dp = [0]*(n+1)

def calc(n):
    global dp
    for i in range(n+1):
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = dp[i-1] + dp[i-2]

def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n-2)

#print(fibonacci(n))
calc(n)
print(dp[n])



2d27c3b0b488c8b1e23a4ad2f13a486b2a4d2807
<mask token>


def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)


<mask token>

<mask token>


def calc(n):
    global dp
    for i in range(n + 1):
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = dp[i - 1] + dp[i - 2]


def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)


<mask token>

<mask token>


def calc(n):
    global dp
    for i in range(n + 1):
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = dp[i - 1] + dp[i - 2]


def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)


calc(n)
print(dp[n])

n = int(input())
dp = [0] * (n + 1)


def calc(n):
    global dp
    for i in range(n + 1):
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = dp[i - 1] + dp[i - 2]


def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)


calc(n)
print(dp[n])

# 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

n = int(input())
dp = [0]*(n+1)

def calc(n):
    global dp
    for i in range(n+1):
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = dp[i-1] + dp[i-2]

def fibonacci(n):
    if n == 0:
        return 1
    if n == 1:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n-2)

#print(fibonacci(n))
calc(n)
print(dp[n])


