#include <stdio.h>
int p;
long m,n;
FILE *f,*g;
int main()
{f=fopen("fact.in","r");
g=fopen ("fact.out","w");
fscanf (f,"%d",&p);
n=0;
if (p==0) fprintf (g,"1");
else
{while (p!=0) {n=n+5;
             m=n;
             while (m%5==0) {p=p-1;
                            m=m/5;}}

if (p<0) fprintf (g,"-1");
          else fprintf (g,"%ld",n);}
          fclose(f);
          fclose(g);


    return 0;
}