def fib(memo,n):
    if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n]

memo = {}
n = int(raw_input())
print fib(memo,n) def fib(memo,n):
    if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n] fib if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n] n in memo n memo return memo[n] memo[n] memo n if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n] n == 0 n 0 return 1 1 elif n == 1:
            return 1
         n == 1 n 1 return 1 1 memo[n] = fib(memo,n-1)+fib(memo,n-2) memo[n] memo n fib(memo,n-1)+fib(memo,n-2) fib(memo,n-1) fib memo n-1 n 1 fib(memo,n-2) fib memo n-2 n 2 return memo[n] memo[n] memo n memo memo n n memo = {} memo {} n = int(raw_input()) n int(raw_input()) int raw_input() raw_input print fib(memo,n) fib memo n memo = {} {} memo n = int(raw_input()) int(raw_input()) n def fib(memo,n):
    if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n] def fib(memo,n):
    if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n] fib
def fib(memo,n):
    if n in memo:
        return memo[n]
    else:
        if n == 0:
            return 1
        elif n == 1:
            return 1
        else:
            memo[n] = fib(memo,n-1)+fib(memo,n-2)
            return memo[n]

memo = {}
n = int(raw_input())
print fib(memo,n)