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| Number | Previous Number(s) | Previous Class | Converted | Use | Withdrawn | Disposal |
| --- | --- | --- | --- | --- | --- | --- |
| 1 | 68845.0 | J52 | 1952.0 | Steam shunter | 1958.0 | Scrapped (1958) |
| 2 (1st) | 68816.0 | J52 | 1952.0 | Steam shunter | 1956.0 | Scrapped (1956) |
| 2 (2nd) | 68858.0 | J52 | 1956.0 | Steam shunter | 1961.0 | Scrapped (1961) |
| 3 | 68181.0 | Y3 | 1952.0 | Steam shunter | 1959.0 | Scrapped (1959) |
| 4 | 68132.0 | Y1 | 1952.0 | Steam shunter | 1959.0 | Scrapped (1959) |
| 5 | 68165.0 | Y3 | 1953.0 | Steam shunter | 1958.0 | Scrapped (1958) |
| 6 | 68133.0 | Y1 | 1953.0 | Steam shunter | 1955.0 | Scrapped (1955) |
| 7 | 68166.0 | Y3 | 1953.0 | Steam shunter | 1964.0 | Scrapped (1964) |
| 8 | 68183.0 | Y3 | 1955.0 | Steam shunter | 1959.0 | Scrapped (1959) |
| 9 | 68840.0 | J52 | 1958.0 | Steam shunter | 1961.0 | Scrapped (1961) |
| 10 | 68911.0 | J50 | 1961.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 11 | 68914.0 | J50 | 1961.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 12 | 68917.0 | J50 | 1962.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 13 | 68928.0 | J50 | 1962.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 14 | 68961.0 | J50 | 1962.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 15 | 68971.0 | J50 | 1962.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 16 | 68976.0 | J50 | 1962.0 | Steam shunter | 1965.0 | Scrapped (1965) |
| 17 | 61059.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 18 | 61181.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1965.0 | Scrapped (1966) |
| 19 | 61204.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 20 | 61205.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1965.0 | Scrapped (1966) |
| 21 (1st) | 68162.0 | Y3 | 1956.0 | Steam shunter | 1960.0 | Scrapped (1960) |
| 21 (2nd) | 61233.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 22 | 61252.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1964.0 | Scrapped (1966) |
| 23 | 61300.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1965.0 | Scrapped (1966) |
| 24 (1st) | 61323.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1963.0 | Scrapped (1964) |
| 24 (2nd) | 61375.0 | B1 | 1963.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 25 | 61272.0 | B1 | 1965.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 26 | 61138.0 | B1 | 1965.0 | Stationary boiler for carriage warming | 1967.0 | Scrapped (1968) |
| 27 | 61105.0 | B1 | 1965.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 28 | 61194.0 | B1 | 1965.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
| 29 | 61264.0 | B1 | 1965.0 | Stationary boiler for carriage warming | 1967.0 | Preserved |
| 30 | 61050.0 | B1 | 1966.0 | Stationary boiler for carriage warming | 1968.0 | Scrapped (1968) |
| 31 (2nd) | 61051.0 | B1 | 1966.0 | Stationary boiler for carriage warming | 1966.0 | Scrapped (1966) |
Question:
What is every previous class when the previous number is 61323?
Answer:
B1