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

int main()
{
   int c,lt,rt,p,n,s,x;
   bool t=false;
   ifstream f("fact.in");
   ofstream g("fact.out");
   f>>p;
   if(p==0) g<<"1";
   else{
   rt=p*5;
   lt=0;
   while(rt-lt!=5)
   {
       c=(lt+(rt-lt)/2)/5;
       c*=5;
       x=1;
       s=0;
       n=0;
       while(x*5<=c)
       {
           s++;
           x*=5;
       }
       x=1;
       for(int i=1;i<=s;++i)
       {
           x*=5;
           n+=(c/x);
       }
       if(n<p) lt=c;
       else if(n>p) rt=c;
            else {t=true; break;}
   }
   if(!t)
   {
       c=rt;
       x=1;
       s=0;
       n=0;
       while(x*5<=c)
       {
           s++;
           x*=5;
       }
       x=1;
       for(int i=1;i<=s;++i)
       {
           x*=5;
           n+=(c/x);
       }
       if(n==p) t=true;
   }
   if(t) g<<c;
   else g<<"-1";
   }
}