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:
| Series # | Season # | Title | Directed by | Written by | Original air date |
| --- | --- | --- | --- | --- | --- |
| 23.0 | 1.0 | "It Happened One Summer (Part 1)" | Asaad Kelada | Martin Cohan & Blake Hunter | September24,1985 |
| 24.0 | 2.0 | "It Happened One Summer (Part 2)" | Asaad Kelada | Martin Cohan & Blake Hunter | October1,1985 |
| 25.0 | 3.0 | "Ad Man Micelli" | Asaad Kelada | Robert Sternin & Prudence Fraser | October8,1985 |
| 26.0 | 4.0 | "The Heiress" | Gary Brown | Alan L. Gansberg | October15,1985 |
| 27.0 | 5.0 | "Tony the Matchmaker" | Asaad Kelada | Paul Robinson Hunter | October29,1985 |
| 28.0 | 6.0 | "Custody (Part 1)" | Asaad Kelada | Robert Sternin & Prudence Fraser | November5,1985 |
| 29.0 | 7.0 | "Custody (Part 2)" | Asaad Kelada | Robert Sternin & Prudence Fraser | November12,1985 |
| 30.0 | 8.0 | "Hunk of the Month" | Michael Zinberg | Karen Wengrod & Ken Cinnmaon | November9,1985 |
| 31.0 | 9.0 | "Thanksgiving at Mrs. Rossini's" | Asaad Kelada | Dawn Aldredge & Judith Bustany | November26,1985 |
| 32.0 | 10.0 | "The Prodigal Father-in-Law" | Asaad Kelada | Cheri Eichen & Bill Steinkellner | December3,1985 |
| 33.0 | 11.0 | "The Graduate" | Asaad Kelada | Bud Wiser | December10,1985 |
| 34.0 | 12.0 | "Tony the Nanny" | Katherine Helmond & Gail L. Bergmann | Ellen Guylas | December17,1985 |
| 35.0 | 13.0 | "Junior Executive" | Tony Danza & Gail L. Bergmann | Cheri Eichen & Bill Steinkellner | January7,1986 |
| 36.0 | 14.0 | "Educating Tony" | Asaad Kelada | Michael Poryes | January14,1986 |
| 37.0 | 15.0 | "Gotta Dance" | Asaad Kelada | Howard Meyers | January21,1986 |
| 38.0 | 16.0 | "The Babysitter" | Asaad Kelada | Bud Wiser | January28,1986 |
| 39.0 | 17.0 | "Jonathan Plays Cupid " | Asaad Kelada | Paul Robinson Hunter | February11,1986 |
| 40.0 | 18.0 | "When Worlds Collide" | Asaad Kelada | Karen Wengrod & Ken Cinnamon | February18,1986 |
| 41.0 | 19.0 | "Losers and Other Strangers" | Asaad Kelada | Seth Weisbord | February25,1986 |
| 42.0 | 20.0 | "Tony for President" | Asaad Kelada | Howard Meyers | March4,1986 |
| 43.0 | 21.0 | "Not With My Client, You Don't" | Asaad Kelada | Dawn Aldredge & Judith Bustany | March18,1986 |
| 45.0 | 23.0 | "There's No Business Like Shoe Business" | Asaad Kelada | Karen Wengrod & Ken Cinnamon | April1,1986 |
| 46.0 | 24.0 | "The Unnatural" | Jim Drake | Ellen Guylas | April8,1986 |
Question:
What is the season where the episode "when worlds collide" was shown?
Answer:
18.0