c# - How to get a random number from a range, excluding some values -

in c#, how random number range of values - 1..100, number should not in specific list of values, 5, 7, 17, 23?

since no-one has posted example code:

private int givemeanumber() {     var exclude = new hashset<int>() { 5, 7, 17, 23 };     var range = enumerable.range(1, 100).where(i => !exclude.contains(i));      var rand = new system.random();     int index = rand.next(0, 100 - exclude.count);     return range.elementat(index); } 

here's thinking:

1. build hashset of numbers want exclude
2. create collection of numbers 0-100 aren't in list of numbers exclude bit of linq.
3. create random object.
4. use random object give number between 0 , number of elements in range of numbers (inclusive).
5. return number @ index.