#include <iostream>
#include <fstream>

using namespace std;

ifstream in("fact.in");
ofstream out("fact.out");
int main()
{
    int p,c=0,k=0,ck=0;
    in >>p;
    if (p==0) {out <<1;return 0;}
    while (c<p){
        k+=5;
        int x=k;
        while (x%5==0){
            x/=5;
            ck++;
            }
        c+=ck;
        ck=0;
    }
    if (c==p)
        out <<k;
    else
        out <<"-1";
}