#include<iostream>
using namespace std;

int fun(int x)
{
    if(x<1)
    return x;
    else if(x<10)
    return 2*x-1;
    else
    return 3*x-11;
}

int main()
{
    int x;
    cin>>x;
    cout<<fun(x);
    return 0;
}