#include <bits/stdc++.h>
using namespace std;
int n, dp[100][100], a, b, c;
int main(){
  cin >> n;
  dp[1][a] = 1;
  dp[1][b] = 1;
  dp[1][c] = 1;
  for(int i = 2; i <= n; i++){
    dp[i][a] += dp[i-1][a];
    dp[i][a] += dp[i-1][c];
    dp[i][b] += dp[i-1][b];
    dp[i][b] += dp[i-1][c];
    dp[i][c] += dp[i-1][a];
    dp[i][c] += dp[i-1][b];
    dp[i][c] += dp[i-1][c];
    dp[i][a]++;
    dp[i][b]++;
    dp[i][c]++;
  }
  cout << dp[n][a] + dp[n][b] + dp[n][c] << endl;
  return 0;
}