#include<fstream>
using namespace std;




int main()
{
    int p;
    ifstream in ("fact.in");
    ofstream out ("fact.out");
    in>>p;

    if (p == 0) out<<1;

    else {
        int fact = 0, zeros;
        for (zeros = 1; zeros <= p; zeros++, fact+=5)
            if ((zeros+1) % 6 == 0) zeros++;
        out<<fact;
    }
    
    out.close();
    return 0;
}