#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
    ll n;
    cin>>n;
    ll j=0,c=0;
    for(ll i=n;i>=0;i-=2){
            ll d=1,k=i+1;
            for(int l=1;l<=j;l++){
              d*=k;
              d/=l;
              k++;
            }
            
            c+=d;
      j++;
    }
    cout<<c<<endl;
}