#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
long long n,s,i=1,p,o2,o5,ok,nr;
int main()
{
    f>>p;
    while(ok==0)
    {
        nr=i;
        while(nr%2==0)nr/=2,o2++;
        while(nr%5==0)nr/=5,o5++;
        if(min(o2,o5)==p){ok=1;g<<i;break;}
        if(min(o2,o5)>p)break;
        i++;
    }
    if(ok==0)g<<-1;
    return 0;
}