var f:text;
    p,r,fac,facc:int64;
begin
assign(f ,'fact.in');
reset(f);
read(f,p);
close(f);
r:=1;
fac:=5;
while r<p do
  begin
   r:=r+fac;
   fac:=fac*5;
  end;
assign(f ,'fact.out');
rewrite(f);
if r=p then
  write(f,fac)
   else
   begin
    while (p<>r) and (p>r) do
     begin
      facc:=fac;
      while facc mod 5=0 do
       begin
        facc:=facc div 5;
        r:=r+1;
       end;
      fac:=fac-5;

     end;
if r=p then
     write(f,fac)
      else
     write(f,'-1');
   end;
     close(f);
end.