#include<fstream>

using namespace std;

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

int nr_zero(int n)
{
    int pw = 5;
    int nr_zero = 0;
    while(pw<=n)
    {
        nr_zero+=n/pw;
        pw*=5;
    }
    return nr_zero;
}

int p,sol,mj;
long long st=0,dr=1000000005;

int main()
{
    in>>p;
    if(p==0) out<<1;
    else
    {
        while(st<=dr)
        {
            mj = (st+dr)/2;
            if(nr_zero(mj)<p)
                st = mj+1;
            else if(nr_zero(mj)>p)
                dr= mj-1;
            else if(nr_zero(mj)==p)
            {
                sol = mj;
                dr = mj-1;
            }
        }
        if(sol==0)
            out<<-1;
        else
            out<<sol;
    }
    return 0;

}