#include <fstream>

using namespace std;

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

const int L=28;
int p, n;

int zero(int n)
{
    int nr=0;
    while(n>=5)
    {
        nr+=n/5;
        n/=5;
    }
    return nr;
}

int main()
{
    in>>p;
    int r=0, pas=1<<L;
    while(pas!=0)
    {
        if(zero(r+pas) < p)
        {
            r+=pas;
        }
        pas/=2;
    }
    r++;
    if(zero(r) > p) r=-1;
    out<<r;

    in.close();
    out.close();
    return 0;
}