#include <iostream.h>
#include <stdio.h>
int main()
{int j,n=0,x=0,i;
long p;

freopen("fact.in", "r", stdin);
freopen("fact.out", "w", stdout);
cin>>p;

if(p==0) {cout<<1; return 0;}
else
 {while(x<p)
   {n=n+5;
    j=n;
    i=1;
    if(n%15625==0) i=6; else
     if(n%3125==0) i=5; else
      if(n%625==0) i=4; else
       if(n%125==0) i=3; else
	if(n%25==0) i=2;
    while(i)
     {j=j/5; --i;}
    x=x+i;}
  if(x==p) cout<<n;
  else cout<<-1;}

fcloseall();
return 0;
}