#include <bits/stdc++.h>
#include<math.h>
using namespace std;
unsigned factorial(unsigned n)
{
    if (n <= 1)
        return 1;
    else
        return n * factorial(n - 1);
}
int main(){
    int n;
    cin >> n;
    vector<int> m(n);
    for(int m_i = 0; m_i < n; m_i++){
       cin >> m[m_i];
    }
    if(n<3)
     cout<<1;
    else
    {   int t=0;
        //cout<<n;
        for(int i=n;i>1;i--)
        {t+=(factorial(n)/(factorial(i)*factorial(n-i)));
        }
        cout<<t;
    }
    // your code goes here
    return 0;
}