var P : longint;
    f : textfile;

function GetZero (N : Integer) : int64;
var i, z : int64;
begin
  z := 1;
  if (N mod 5 = 0) and (N <> 0)
    then z := -1
    else
      while N > 0 do
        begin
          N := N div 5;
          z := z * 5;
        end;

  GetZero := z;
end;

begin
  Assign(f, 'fact.in');
  Reset(f);
  Read(f, P);
  Close(f);

  Assign(f, 'fact.out');
  Rewrite(f);
  Write(f, GetZero(P));
  Close(f);
end.