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:
| Episode No. Episode No. refers to the episodes number in the overall series, whereas Series No. refers to the episodes number in this particular series. | Series No. | Episode | Director | Writer | Original airdate |
| --- | --- | --- | --- | --- | --- |
| 66.0 | 1.0 | "Humpty Dumpty" | Jim Hill | Ginnie Hole | 6September1991 |
| 67.0 | 2.0 | "Judgement Day" | Margy Kinmonth | Barbara Machin | 13September1991 |
| 68.0 | 3.0 | "Dangerous Games" | Charles McDougall | Robin Mukherjee | 20September1991 |
| 69.0 | 4.0 | "Hide and Seek" | Jim Hill | David Richard-Fox | 27September1991 |
| 70.0 | 5.0 | "Joy Ride" | Steve Goldie | Bill Gallagher | 4October1991 |
| 71.0 | 6.0 | "Something to Hide" | Steve Goldie | Stephen Wyatt | 11October1991 |
| 72.0 | 7.0 | "Beggars Can't Be Choosers" | Alan Wareing | Ginnie Hole | 18October1991 |
| 73.0 | 8.0 | "Living in Hope" | Margy Kinmonth | Robin Mukherjee | 25October1991 |
| 74.0 | 9.0 | "Making the Break" | Jim Hill | Jacqueline Holborough | 1November1991 |
| 75.0 | 10.0 | "Sins of Omission" | Alan Wareing | Bryan Elsley | 8November1991 |
| 76.0 | 11.0 | "The Last Word" | Michael Owen Morris | Barbara Machin | 15November1991 |
| 77.0 | 12.0 | "Pressure! What Pressure?" | Michael Brayshaw | Arthur McKenzie | 29November1991 |
| 78.0 | 13.0 | "Facing Up" | Bill Pryde | Bill Gallagher | 6December1991 |
| 79.0 | 14.0 | "Allegiance" | Alan Wareing | David Richard-Fox | 15December1991 |
Question:
Name the least series number for episode number being 78
Answer:
13.0