#include <iostream>
#include <fstream>

using namespace std;

ifstream in ("fact.in");
ofstream out("fact.out");

long long P, Number;

long long Shearch_Fact (long long P) {

    if (P == 0) { out << 1;
                  return 0; }

    if (P == 1) { out << 10;
                  return 0; }
    Number = 5;
    for (int Cont = 2; Cont < P; ++Cont) {
            Number += 5;
    }

return Number;
}

main () {

    in >> P;
    out << Shearch_Fact (P);
}