Count the number of elements in a Set<String> that match a specific pattern. The pattern is a string that can be found at the beginning, end, or within the elements.

Examples:

Input: set = {"ApexClass", "ApexTrigger", "CustomObject", "ApexPage"} pattern = "Apex" Output: 3 Explanation: "ApexClass", "ApexTrigger", and "ApexPage" all contain "Apex" Input: set = {"Contact", "Account", "Opportunity", "Lead"} pattern = "t" Output: 2 Explanation: "Contact" and "Opportunity" both contain the letter "t"
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