#include <fstream>
#include <set>

using namespace std;
set < long long  > S;
int main()
{
    ifstream f("dtcsu.in");
    /*int i,Q, sol = 0;
    long long x;
    for(i = 1; i<= 276997;++i)
    {
        f >> x;
        if(x&1)
            S.insert(x);
    }
    for(f >> Q; Q;--Q)
    {
        f >> x;
        if(x && S.lower_bound(x/(x&(-x)))!=S.end())
            ++sol;
    }*/
    int n;
    f >> n;
    ofstream g("dtcsu.out");
    g<<n*2<<"\n";
    g.close();
    return 0;
}