/*
TASK:necklace
LANG:C++
*/
#include<iostream>
using namespace std;
long long a[70];
int n;
int main(){
    a[1]=0;
    cin >> n;
    for(int i=2;i<=n;i++)
    if(i%2==0) a[i]=(a[i-1]*2)+1; else a[i]=(a[i-1]*2)-1;
    cout << a[n] << '\n';
    return 0;
}
