#include <iostream>
#include <fstream>

using namespace std;

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

long Fact(long P)
{
    if(P==0)
        return 1;

    long result=5;
    while(P)
    {
        long aux=result;
        int nr=0;
        while(aux%5==0)
            {nr++;aux/=5;}
        P-=nr;
        result+=5;
    }

    if (P < 0)
        return -1;

    return result-5;

}
int main()
{
    long P;
    in>>P;
    out<<Fact(P);
    return 0;
}