//Bai 16
 
#include<bits/stdc++.h>
using namespace std;
#define el "\n"
#define ll long long
#define ull unsigned long long
#define se second
#define fi first
#define be begin()
#define en end()
#define Faster cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
int n;
ll solve(int n)
{
    if(n == 0) return 1;
    if(n == 1) return 2;
    return 3*solve(n-1) - 2*solve(n-2);
}
void Run()
{
    cin >> n;
    cout << solve(n);
}
int main()
{
    Faster;
    Run();
    return 0;
}
 
 

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