#include <iostream>
#include <fstream>
using namespace std;
ifstream f("croseta.in");
ofstream g("croseta.out");
int verif(int k)
{
    int s=0;
    while (k)
    {
        if (k==2)
            s++;
        s=s+k;
        k=k/3;
    }
    return s;
}
int main()
{
    int n,p,u,m,ok,y;
    f>>n;
    n=n/2;
    p=1;u=n;ok=0;
    while (p<=u && ok==0)
    {
        m=(p+u)/2;
        y=verif(m);
        if (y==n)
            g<<m, ok=1;
        else if (y<n)
            p=m+1;
        else u=m-1;
    }
    return 0;
}