#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int p;
int v;
int a[500];
int ridicare(int x)
{
    int r=1,p=5;

    while(x!=0){
        if(x%2==1)r=r*p;
        p=p*p;
        x=x/2;
    }
   return r;
}
bool t=true;
int cautare()
{
  long long s1=0;
  long long s;
  while(p>0){s=0;
  v=0;
    while(5*s+1<=p){v++;
      s=5*s+1;
    }
    if(p/s>=5){
        g<<"-1";t=false;
        break;

    }
    else{
    s1=s1+(p/s)*ridicare(v);
    p=p-s*(p/s);
    }
  }
if(t==true)g<<s1;
}
int main()
{
    f>>p;
    cautare();
    return 0;
}