Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Creature (Other Planes) | Page | Other Appearances | Variants | Description |
| --- | --- | --- | --- | --- |
| Aerial Servant | 39 | Rules Cyclopedia (1991) |  |  |
| Basilisk | 39 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Cockatrice | 39 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Djinni, Lesser | 39 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Djinni, Greater | 39 | Rules Cyclopedia (1991) |  |  |
| Efreeti, Lesser | 39 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Efreeti, Greater | 39-40 | Rules Cyclopedia (1991) |  |  |
| Elemental | 40 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional statistics and abilities/penalties applicable to native plane of existence. |
| Gorgon | 40 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Helion | 40 | Rules Cyclopedia (1991) |  |  |
| Horde | 41 | Rules Cyclopedia (1991) |  |  |
| Hydrax | 41 | Rules Cyclopedia (1991) |  |  |
| Invisible Stalker | 41 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Kryst | 42 | Rules Cyclopedia (1991) |  |  |
| Medusa | 42 | D&D Basic Rules (1981), D&D Basic Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Plasm | 42 | Rules Cyclopedia (1991) | Normal and giant |  |
| Salamander | 42 | D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991) |  | Describes additional abilities/penalties applicable to native plane of existence. |
| Undine | 42 | Rules Cyclopedia (1991) |  |  |
Question:
how many creatures are on page 40?
Answer:
4