I could not find or figure out similar LINQ example.

For the example, I have 2 lists:

List<List<string>> cases = new List<List<string>>()
{
    new List<string>() { "a", "c", "b", "w", "z" },
    new List<string>() { "s", "c", "b", "w", "z" },
    new List<string>() { "t", "c", "b", "w", "z" },
    new List<string>() { "u", "c", "b", "w", "z" },
};

and

List<List<string>> pairs = new List<List<string>>()
{
    new List<string>() { "a", "r" },
    new List<string>() { "a", "f" },
    new List<string>() { "u", "f" },
    new List<string>() { "u", "z" },
};

I need to get cases that contains all elements of ANY of pairs. How to do it with LINQ?

My best try is:

var res = pairs.Where(x => cases.All(y => x.All(z => y.IndexOf(z) >= 0))).ToList();

But gives no results :/