#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");

int main()
{
    long long nrzero,cinci=0,numar=0,valrez=0;
    fin>>nrzero;
    //Sarituri mari
    while(nrzero>0)
    {
        numar=numar+5;
        valrez=numar;
        while(valrez%5==0)
        {
            valrez=valrez/5;
            cinci++;
        }
        while(cinci!=0)
        {
            cinci--;
            nrzero--;
        }
    }
    if(nrzero==0)
        fout<<numar;
    else
        fout<<-1;
    fin.close();
    fout.close();
    return 0;
}