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:
| Class | Wheel arrangement | Fleet number(s) | Manufacturer | Year made | Quantity made | Quantity preserved |
| --- | --- | --- | --- | --- | --- | --- |
| 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation | 2-8-0 — oOOOO — Consolidation |
| F-1 | 2-8-0 | 403–405, 407–412 | Schenectady | 1893 | 9 | 0 |
| F-2 | 2-8-0 | 406 | Schenectady | 1893 | 1 | 0 |
| F-3 | 2-8-0 | 413–416 | Schenectady | 1893 | 4 | 0 |
| F-4 | 2-8-0 | 417 | Schenectady | 1893 | 1 | 0 |
| F-6 | 2-8-0 | 400–402, 418–427 | Rhode Island | 1893 | 13 | 0 |
| F-7 | 2-8-0 | 428–430 | Schenectady | 1900 | 3 | 0 |
| F-8 | 2-8-0 | 431–444 | Alco -Schenectady | 1902–1903 | 14 | 1 |
| F-9 | 2-8-0 | 445–472 | Alco -Schenectady | 1905–1906 | 28 | 1 |
| F-10 | 2-8-0 | 473–474 | Alco -Schenectady | 1909 | 2 | 0 |
| F-11 | 2-8-0 | 475–484 | Alco -Schenectady | 1910 | 10 | 0 |
| F-12 | 2-8-0 | 485–499 | Alco -Schenectady | 1912–1913 | 15 | 0 |
| F-20 | 2-8-0 | 2400–2424 | Alco -Schenectady | 1903–1907 | 25 | 1 |
| F-21 | 2-8-0 | 2425–2428 | Alco -Schenectady | 1909 | 4 | 1 |
| F-22 | 2-8-0 | 2429–2443 | Alco -Schenectady | 1911 | 15 | 1 |
| F-23 | 2-8-0 | 2444–2450 | Alco -Schenectady | 1914 | 7 | 0 |
Question:
What is the quantity preserved when 4 were made of class F-21?
Answer:
1.0