#include<iostream>
using namespace std;
class st{
    private:
            int top;
            int STACK[100];
    public:
            int Create(){
            top = 0;
            }
            int howhigh(){return top;}
            int isempty(){return (top==0?1:0);}
            int push(int cine)
            {
                if(howhigh()<100)
                    STACK[++top]=cine;
                return 0;
            }
            int pop()
            {
                if (isempty())
                    return 0;
                return STACK[top--];
            }
            int tops()
            {
                return STACK[top];
            }
};

int mp(int x);

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

int mp(int x)
{
    st Stiva;
    Stiva.Create();
    Stiva.push(x);

    int fost1, fost2;
    while(Stiva.howhigh() > 0)
    {
        if(Stiva.tops() < 12)
        {
            Stiva.push(Stiva.tops()+2);
        }
        else
        {
            fost1 = Stiva.pop();
            if((fost2 = Stiva.pop()))
                Stiva.push(fost1 - 1);
        }
    }
    Stiva.push(fost1-1);

    return Stiva.pop();
}