#include<iostream.h>
#include<fstream.h>
 using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
 
int main()
{
  
long p,ok=0,n,doi=0,cinci=0,pp;
    in>>p;
 
    for(n=1;ok==0 && n>0;n++)
    {
        pp=n;
        while(pp%5==0){
            if (pp%5==0) { cinci++; pp=pp/5;}
            }
 
        if(cinci>=p)
            ok=n;
    }
 
    if(cinci != p) out<<-1;
    else out<<ok;
 
    out.close();
    in.close();
 
    return 0;
}