#include<fstream>
#include<cmath>
using namespace std;
int div2(int n)
{
    int p1=0;
    while(n%2==0) {p1++;n/=2;}
    return p1;
}
int div5(int n)
{
    int p1=0;
    while(n%5==0) {p1++;n/=5;}
    return p1;
}
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    int nr1=0,nr2=0;
    long int x=1,P;
    f>>P; f.close();
    if(!P) {g<<1;return 0;}
    do
    {
        nr1+=div2(x);
        nr2+=div5(x);
        x++;
        if(x>pow(10,P)) {g<<-1; break;}
    }while(nr1<P||nr2<P);
    g<<x-1; g.close();
    return 0;
}