#include <iostream>
#include <fstream>

using namespace std;

long x,z;
int i,n,p,j;
int main()
{
    z=10;
    n=1;
    x=1;
    j=1;
    ifstream f("fact.in");
        f>>p;
    while(p>0)
    {
        x=x*10;
        z=z*10;
        p=p-1;
    }
    for(i=1;i<=n;i++)
    {
        n=n+1;
        j=(j*i)%z;
        if(j%x==0)
            {
                if(j%z==0)
                {
                    ofstream g("fact.out");
                    g<<-1;
                    return 0;
                }
                ofstream g("fact.out");
                g<<i;
                return 0;
            }

    }
    return 0;
}