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:
| Rank | Name | Nationality | Time |
| --- | --- | --- | --- |
|  | Mark Henderson | United States | 54.11 |
|  | Eduardo Piccinini | Brazil | 54.63 |
|  | Brian Alderman | United States | 54.75 |
| 4 | Francisco Sánchez | Venezuela | 54.99 |
| 5 | Edward Parenti | Canada | 55.23 |
| 6 | Diego Cuenca | Colombia | 55.67 |
| 7 | José Meolans | Argentina | 55.91 |
| 8 | Ruben Calderon | El Salvador | 56.04 |
Question:
how many swimmers swam the 100 meters in under 55 seconds?
Answer:
4