#include <stdio.h>
#include <stdlib.h>
#include<math.h>
using namespace std;
unsigned long p, nr=0,i;
int cinci(unsigned long p)
{
    int pu=0;
    while(p%5==0)
        {pu++;
        p=p/5;
        }
    return pu;
}
unsigned long putere(unsigned long p, unsigned long &nr)
{
    if(p==0)
        nr=1;
    else
    {
        unsigned long pu=0;
        int gasit=0;
        for(i=5;i<=pow(5,8) && !gasit;i=i+5)
        {
            pu=i/5;
            if(i/5>=5)
                {nr=i/5;
                while(nr/5>0)
                {
                    pu++;
                    nr=nr-5;
                }}
            if(pu==p)
                {gasit=1;
                nr=i;
                }
        }
    }
    return nr;
}
int main()
{
    FILE *f;
    FILE *g;
    f = fopen("fact.in","r");
    g = fopen("fact.out","w");
    fscanf(f,"%lu",&p);
    if (putere(p,nr)==0)
    fprintf(g,"%i\n",-1);
    else
    fprintf(g,"%lu\n",nr);
    fclose(g);
    fclose(f);
    return 0;
}