#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
void solve(int p)
{
    int x=0;
    int64_t pow5=25;
    int k=0,y=2;
    while(k<p) {
        x+=5;
        if(x==pow5) {
            k+=y;
            y++;
            pow5*=5;
        }
        else
            k++;
    }
    if(!k)
        g<<1;
    else if(k==p)
        g<<x;
    else
        g<<-1;
    g<<'\n';
    f.close();
    g.close();
}
int main()
{
    int p;
    f>>p;
    solve(p);
    return 0;
}