user
Instruction
Answer the question based on the provided table.


Table
Table Title: List of operas by Siegfried Wagner
Table Content:
| Opus | Title | Sub­divisions | Compo-sition | Première date | Place, theatre |
| --- | --- | --- | --- | --- | --- |
| 1 | Der Bärenhäuter | 3 acts | 1898 | 22 January 1899 | Munich, Hofopera |
| 2 | Herzog Wildfang | 3 acts | 1900 | 23 March 1901 | Munich, Hofopera |
| 3 | Der Kobold | 3 acts | 1903 | 29 January 1904 | Hamburg, Stadttheater |
| 4 | Bruder Lustig | 3 acts | 1904 | 13 October 1905 | Hamburg, Stadttheater |
| 5 | Sternengebot | prologue and 3 acts | 1906 | 21 January 1908 | Hamburg, Stadttheater |
| 6 | Banadietrich | 3 acts | 1909 | 23 January 1910 | Karlsruhe, Hoftheater |
| 7 | Schwarzschwanenreich | 3 acts | 1910 | 5 November 1918 | Karlsruhe, Hoftheater |
| 8 | Sonnenflammen | 3 acts | 1912 | 30 October 1918 | Darmstadt, Hoftheater |
| 9 | Der Heidenkönig | prologue and 3 acts | 1913 | 16 December 1933 | Cologne, Städtische Bühnen |
| 10 | Der Friedensengel | 3 acts | 1914 | 4 March 1926 | Karlsruhe, Badisches Landestheater |
| 11 | An allem ist Hütchen Schuld! | 3 acts | 1915 | 6 December 1917 | Stuttgart, Hofopera |
| 12a | Das Liebesopfer (libretto only, no music completed) | 4 acts | 1917 |  |  |
| 13 | Der Schmied von Marienburg | 3 acts | 1920 | 16 December 1920 | Rostock, Städtische Bühnen |
| 14 | Rainulf und Adelasia | 3 acts | 1922 | 1923 | Rostock (prelude only) |
| 15 | Die heilige Linde | 3 acts | 1927 | 2001 | Keulen (prelude only) |
| 16 | Wahnopfer | 3 acts | 1928 | 1994 | Rudolstadt, Heidecksburg only libretto and Act 1 finished |
| 17 | Walamund (libretto only, no music completed) | 3 acts | 1928 |  |  |
| 18 | Das Flüchlein, das Jeder mitbekam | 3 acts | 1929 | 29 April 1984 | Kiel (completed by Hans Peter Mohr) |


Question
how many titles were listed as having 3 acts and a prologue?


Answer Format
The final answer should be concise and use the following format:
```json
{
    "answer": [
        "answer1",
        "answer2",
        ...
    ]
}
```
rule
["2"]