#include<bits/stdc++.h>
using namespace std;

#define FOR(i,a,b) for(int i = (a); i < (b); i++)

#define rep(i,n) FOR(i,0,n)
#define RFOR(i,b,a) for(int i = (b) - 1; i>= (a); i--)
#define ITER(it, a) for(typeof(a.begin()) it = a.begin(); it != a.end(); it++)
#define FILL(a, value) memset(a, value, sizeof(a)

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair

typedef unsigned long long LL;
typedef vector<int> VI;
typedef vector<bool>VB;
typedef pair<int, int> PII;

const double PI = acos(-1.0);
const int INF = 1000 * 1000 * 1000 + 7;
const LL LINF = INF * (LL)INF;

const double EPS = 1e-7;
const int MAX = 20 * 1000 + 47;
const int MOD = 1000 * 1000 * 1000 + 7;
const int MAS = 1000 * 100;

vector<int> add(VI & a, VI & b )
{
 VI res = a;
 if (res.size() == 0)
 {
     res.push_back(0);
 }
    while(res.size() < b.size())
    {
        res.push_back(0);
    }
    while(b.size() < res.size())
    {
        b.push_back(0);
    }
    int nxt = 0 ;
    rep(i,res.size())
    {
        res[i] += b[i] + nxt;

        if (res[i] >= 10) {
            nxt = 1;
            res[i] -= 10;
        } else {
            nxt = 0;
        }


    }
    if (nxt == 1)
    {
        res.PB(nxt);
    }
    return res ;


}

vector<int> dp[1000][4];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n ;
    cin >> n;
    dp[0][1].PB(1);
    dp[1][2].PB(1);
    dp[2][3].PB(1) ;
    dp[2][2].PB(1) ;
    dp[2][1].PB(1);
    FOR(i,3,n )
    {
        dp[i][1] = add(dp[i-1][2],dp[i-1][3]) ;
        dp[i][2] =add(dp[i-2][1],dp[i-2][3]);
        dp[i][3] =add(dp[i-3][1],dp[i-3][2]);

    }
    VI res1 = add(dp[n-1][1],dp[n-1][2]);
    VI res2 = add(res1,dp[n-1][3]);
    for(auto it = res2.begin();it!=res2.end();it++ )
    cout<<*it;

}