#include <fstream>
#include <iostream>

using namespace std;

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

int nrmax=100000000;

int zero(int x) {
    int sol=0;
    while (x/5!=0) {
        sol=sol+x/5;
        x=x/5;
    }
    return sol;
}

int main () {
    int n,i,Sol,n2;
    fin>>n;

    for (n2=1; n2<=5*nrmax; n2*=2) {
    }
    n2/=2;

     Sol=5*nrmax;
    for (i=n2; i>0; i/=2)
        {
         if (Sol-i>=1 && zero(Sol-i)>=n)
            Sol=Sol-i;
        }

    if (zero(Sol)==n)
        fout<<Sol<<"\n";
     else  fout<<"-1\n";



    return 0;
}