#include <fstream>      
#include <iostream>      
#include <math.h>      
     
using namespace std;      
     
long divizori( long &x)      
{      
     long putere=0,cinci=0;      
     while (cinci*5+1<=x){cinci=cinci*5+1; putere=putere+1;}      
     
     x=x-cinci;      
          
     return (long)ceil(pow(5,putere));      
     }      
           
int main()      
{      
    long p,n,aux;      
    ifstream f("fact.in");      
    f>>p;      
    f.close();      
         
    n=0;      
long adun;      
     
if (p==0) n=1;      
else     
while (p>0)      
 {adun=divizori(p);      
  n=n+adun;      
}              
           
             
     
ofstream g("fact.out");      
 g<<n;      
g.close();      
      return 0;      
}