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:
| Platform | Frequency (per hour) | Destination | Operator | Line |
| --- | --- | --- | --- | --- |
| 1.0 | 4.0 | Highbury & Islington | London Overground | East London |
| 1.0 | 4.0 | Dalston Junction | London Overground | East London |
| 1.0 | 4.0 | London Bridge | Southern | Metro |
| 2.0 | 4.0 | Crystal Palace | London Overground | East London |
| 2.0 | 4.0 | West Croydon | London Overground | East London |
| 2.0 | 2.0 | London Victoria (Mon-Sat) | Southern | Metro |
| 2.0 | 2.0 | Caterham (Mon-Sat) | Southern | Metro |
| 2.0 | 2.0 | West Croydon (Peaks & Sun only) | Southern | Metro |
| 2.0 | 2.0 | Tattenham Corner (Sun only) | Southern | Metro |
Question:
what is the highest platform number when the frequency (per hour) is 4, the operator is london overground and the destination is west croydon?
Answer:
2.0