Please assist with code in c# or java

line 13 is stack

public Stack=new Stack(); public string[] openingtags; public string [] closingtags;

public String checkHTMLDocument(ArrayList Tags) in class HTML. /* In the hypertext markup language (HTML), tags exist in both opening * and closing forms (refer to the examples in the question paper). * For an HTML document to be correctly formatted, the nested opening * and closing forms of the tags must be properly balanced. * * pre: Have list of tags (Tags) extracted from an HTML document recorded * in sequence of occurrence in HTML document. The list may be empty. * Each tag in list Tags is a string. List Tags has only values occurring * in arrays openingTags or closingTags (see lines 15 and 16). * post: Making use of ONLY the data structure implemented in line 13, * process list Tags to determine whether the HTML document represented * by the list is correctly formatted or not. * For a correctly formatted document return the value SUCCESS. * For an incorrectly formatted document, return the value FAIL. */ {

}