#include <bits/stdc++.h>

using namespace std;

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

unsigned long long p, k, res;

int main()
{
    fin >> p;
    if(p < 0)
    {
        fout << -1;
        return 0;
    }
    for(int i = 1; k <= p; i ++)
        if(i % 10 == 0)
            k += 2, res = i;
        else if(i % 5 == 0)
            k ++, res = i;
    fout << res;
    return 0;
}