Write a function that returns a sorted vector
with the difference of the sorted vectors *v1* and *v2*.
The result must have the elements in *v1* that are not in *v2*,
without repetitions.
For instance, the result of the difference of a vector with 1, 2, 2, 5, 5 and 7
and a vector with 2, 3, 3 and 7 is a vector with 1 and 5.

**Interface**

C++ | vector<double> difference(const vector<double>& v1, const vector<double>& v2); |

Java | public static double[] difference(double[] v1, double[] v2); |

Python | difference(v1, v2) # returns list |

difference(v1: list, v2: list) -> list |

**Observation**
You only need to submit the required procedure;
your main program will be ignored.

Information

- Author
- Salvador Roura
- Language
- English
- Translator
- Carlos Molina
- Original language
- Catalan
- Other languages
- Catalan
- Official solutions
- C++ Java Python
- User solutions
- C++ Python