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TEX is a typesetting language developed by Donald Knuth. It takes source text together with a fewtypesetting instructions and produces, one hopes, a beautiful document. Beautiful documents use “and ” to delimit quotations, rather than the mundane " which is what is provided by most keyboards.Keyboards typically do not have an oriented double-quote, but they do have a left-single-quote ` anda right-single-quote '. Check your keyboard now to locate the left-single-quote key ` (sometimescalled the “backquote key”) and the right-single-quote key ' (sometimes called the “apostrophe” orjust “quote”). Be careful not to confuse the left-single-quote ` with the “backslash” key \. TEX letsthe user type two left-single-quotes `` to create a left-double-quote “ and two right-single-quotes ''to create a right-double-quote ”. Most typists, however, are accustomed to delimiting their quotationswith the un-oriented double-quote ".If the source contained"To be or not to be," quoth the bard, "that is the question."then the typeset document produced by TEX would not contain the desired form:“To be or not to be,” quoth the bard, “that is the question.”In order to produce the desired form, the source file must contain the sequence:``To be or not to be,'' quoth the bard, ``that is the question.''You are to write a program which converts text containing double-quote (") characters into textthat is identical except that double-quotes have been replaced by the two-character sequences requiredby TEX for delimiting quotations with oriented double-quotes. The double-quote (") characters shouldbe replaced appropriately by either `` if the " opens a quotation and by '' if the " closes a quotation.Notice that the question of nested quotations does not arise: The first " must be replaced by ``, thenext by '', the next by ``, the next by '', the next by ``, the next by '', and so on.InputInput will consist of several lines of text containing an even number of double-quote (") characters.Input is ended with an end-of-file character.OutputThe text must be output exactly as it was input except that:• the first " in each pair is replaced by two ` characters: `` and• the second " in each pair is replaced by two ' characters: ''.Sample Input"To be or not to be," quoth the Bard, "thatis the question".The programming contestant replied: "I must disagree.To `C' or not to `C', that is The Question!"Sample Output``To be or not to be,'' quoth the Bard, ``thatis the question''.The programming contestant replied: ``I must disagree.To `C' or not to `C', that is The Question!''