#include <iostream>
#include <fstream>
using namespace std;
long j,i,x,p,nr=0,n;
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    f>>p;
    if (p==0) {g<<1;return 0;}
    else
    for (i=p*4;i<=p*5;i++)
    {
        nr=0;
        for (j=1;j<=i;j++)
        {
            x=j;
            while (x%5==0)
            {
                nr++;
                x=x/5;
            }
        }
        if (nr==p) {g<<i;return 0;}
    }
    g<<-1;
    return 0;
}