#include <iostream>
#include <fstream>
using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");
long long p,nr,i=5;

int main()
{
    f>>p;
    long x;
    while(nr<p)
    {
        x=i;
        while(x%5==0)
        {
            nr++;
            x/=5;
        }
        i+=5;
    }
    if(nr==p)g<<i-5;
    else g<<-1;
    return 0;
}