#include <iostream>
#include<fstream>
using namespace std;

int main()
{long p,n=0,s=0,x;
   ifstream f("fact.in");
   ofstream g("fact.out");
   f>>p;
   if (p==0) g<<1;
       else {while (p<s) {n=n+5; x=n;
                         while(x%5==0) {x=x/5;
                                        s++;} }
            if(p==s) g<<n;
                  else g<<"-1";}
   f.close();
   g.close();
    return 0;
}