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:
| Number | Builder | Entered service | Withdrawn | Notes |
| --- | --- | --- | --- | --- |
| 439 | NZR Addington | 9-1-1909 | 2-3-1957 | Converted to 4-cylinder simple, 6-1949 |
| 440 | NZR Addington | 25-3-1909 | 2-3-1957 | Converted to 4-cylinder simple, 7-1948 |
| 441 | NZR Addington | 10-5-1909 | 2-3-1957 |  |
| 442 | NZR Addington | 10-7-1909 | 4-3-1944 | Converted to 4-cylinder simple, 6-1943. In Use Ohai Railway Board 1944-1968. Preserved at Feilding and District Steam Rail Society |
| 443 | NZR Addington | 1-12-1909 | 2-3-1957 | Converted to 4-cylinder simple, 7-1947 |
| 444 | NZR Addington | 3-2-1910 | 2-3-1957 | Converted to 4-cylinder simple, 12-1949 |
| 445 | NZR Addington | 24-5-1910 | 26-5-1949 |  |
| 446 | NZR Addington | 30-4-1910 | 6-12-1946 | Converted to 4-cylinder simple, 12-1946. In Use Ohai Railway Board 1946-1959. |
| 588 | NZR Addington | 14-10-1913 | 2-3-1957 | Converted to 4-cylinder simple, 5-1951 |
| 589 | NZR Addington | 11-11-1949 | 6-1949 |  |
| 590 | NZR Addington | 27-1-1914 | 2-3-1957 |  |
| 591 | NZR Addington | 17-3-1914 | 2-3-1957 | Converted to 4-cylinder simple, 12-1950 |
| 592 | NZR Addington | 22-6-1914 | 2-3-1957 | Converted to 4-cylinder simple, 10-1950 |
| 593 | NZR Addington | 3-9-1914 | 2-3-1957 | Converted to 4-cylinder simple, 6-1950 |
| 594 | NZR Addington | 31-10-1914 | 2-3-1957 | Converted to 4-cylinder simple, 5-1945 |
| 595 | NZR Addington | 3-12-1914 | 2-3-1957 |  |
| 596 | NZR Addington | 26-1-1915 | 2-3-1957 | Converted to 4-cylinder simple, 12-1949 |
| 597 | NZR Addington | 1-4-1915 | 2-3-1957 |  |
Question:
how many of these locomotives were eventually converted to 4-cylinder simple engines?
Answer:
12