#include <fstream>

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

int Verifica(int numar)
{
    int putere = 0;
    while(numar%5==0)
    {
        putere++;
        numar/=5;
    }
    return putere;
}

int main()
{
    int p,aux,i,cnt;
    bool ok = false;
    fin>>p;
    aux = p;
    if(aux%5==0 &&aux!=0)
    {
        while(aux%5==0)
            aux/=5;
        if(aux==1) ok = true;
    }
    cnt = 0;
    if(p==0) fout<<"1\n";
    else if(ok==false)
    {
        i = 5;
        while(cnt<p)
        {
            cnt+=Verifica(i);
            i+=5;
        }
        fout<<i-5<<"\n";
    }
    else if(ok==true) fout<<"-1\n";



    fout.close();
    return 0;
}