#include <fstream>
#include <cmath>
using namespace std;
ifstream f("DATE.IN");
ofstream g("date.out1");
int main()
{
    int  N,P,x,a;
    f>>P;
    if (P==0) g<<1;
    N=0;
    do
    {
        N=N+5;
        x=0;
        a=5;
        while (a<=N)
        {
            x=x+N/a;
            a=a*5;
        }
    } while(x<P);
    if(x==P) g<<N;
             else g<<"-1";

return 0;
}