#include <fstream>

using namespace std;
ifstream in ("fact.in");
ofstream out ("fact.out");

bool put(long long a)
{
    long long z=1;
    if(a<=5)
        return 0;
    while(z<a)
        z*=5;
    return z==a;
}

long long nrz(long long n)
{
    long long i=0,nr=0,z=1,a=2;
    if(n==0)
        return 1;
    else
    {
        while(nr<n)
        {
            if(put(i+5))
            {
                nr=nr+a;
                a++;
            }
            else
            {
                nr++;
            }
            i=i+5;
        }
    }
    if(nr==n)
        return i;
    else
        return -1;
}
int main()
{
    long long n,r;
    in>>n;
    r=nrz(n);
    out<<r;
    return 0;
}