/*
TASK:necklace
LANG:C++
*/
#include<iostream>
#include<math.h>
using namespace std;
int main()
{
 long long n;
    cin>>n;
    cout<<((long long)pow((long long)2,(long long)n)/(long long)2+(long long)1)/(long long)3;
    cout<<endl;
    return 0;
}
    
	
