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:
| Children of Earth | Run time | Writer | Director | Original airdate | Viewers (including HD) in millions |
| --- | --- | --- | --- | --- | --- |
| "Day One" | 1 hour | Russell T Davies | Euros Lyn | 6 July 2009 | 6.472 (6.601) |
| "Day Two" | 1 hour | John Fay | Euros Lyn | 7 July 2009 | 6.136 (6.248) |
| "Day Three" | 1 hour | Russell T Davies and James Moran | Euros Lyn | 8 July 2009 | 6.397 (6.557) |
| "Day Four" | 1 hour | John Fay | Euros Lyn | 9 July 2009 | 6.756 (6.883) |
| "Day Five" | 1 hour | Russell T Davies | Euros Lyn | 10 July 2009 | 6.581 (6.732) |
Question:
Who is the writer of Children of Earth of "day four"?
Answer:
John Fay