#include<stdio.h>
int main()
{
 freopen ("fact.in","rt",stdin);
 freopen ("fact.out","wt",stdout);
 long p5[13],v[13],n=0,p,i;
 scanf("%ld",&p);
 v[1]=1;
 p5[1]=5;
 for(i=1;v[i]<=p;i++)
  {
   v[i+1]=v[i]*5+1;
   p5[i+1]=p5[i]*5;
  }
 i--;
 while(p>5&&i>0)
 {
  n+=p5[i]*(p/v[i]);
  p-=(p/v[i])*v[i];
  i--;
 }
 if(p==5) printf("-1\n");
  else printf("%ld\n",n+p*5);
 return 0;
}