#include <stdio.h>
#include <fstream>
#include <iostream>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");
int main()
{
    int qwe=0,zxc;
    unsigned p;
    f>>p;
    if (p==0){
     g<<1;   
    }
    else {
    if ((p%6)==(5%6)){
        g<<-1;
    }
    else{
    zxc=p*5;
        while (zxc/25!=0){
            qwe+=1;
        zxc/=25;
        }
        g<<(p-qwe)*5;
    }
    }
    return 0;
}