#!/bin/python

def count_subsets(n, subsets):
    import math
    
    if n == 0 or subsets == 0:
        return 0
    if subsets == 1 or subsets == n:
        return 1
    n -= subsets
    res = 1
    while n > subsets:
        res *= math.factorial(subsets)
        n -= subsets
    res = res * math.factorial(subsets) / math.factorial(n)
    return res
    
import sys


n = int(raw_input().strip())
m = map(int, raw_input().strip().split(' '))
# your code goes here
res = 0
for subsets in xrange(1, n + 1):
    res += count_subsets(n, subsets)
print res