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+The problem is to determine how many different ways there are to make
+change for a given amount using five denominations of US coins
+(including the 50-cent piece). One version -- taken directly from
+section 1.2.2 of Abelson and Sussman (1st edition, 1985) -- recurses
+both towards lower amounts and fewer kinds of coins.  The space
+required by this tree recursion grows rapidly with the size of the
+problem. The other version is a minor modification which makes the
+long ``amount'' direction tail-recursive. The ``kinds'' direction is
+still recursive, but with only five kinds of coins there need be only
+five stack frames for the routine allocated at a time.
+
+In case it isn't obvious, the routine starting at (100) is the
+function ``first-denomination'' (one of the few things INTERCAL can do
+easily), the one at (200) is the recursive version ``cc'', and (300)
+starts the tail-recursive routine ``cc-tail''. The first few lines are
+the main program, which you can change to run the recursive version by
+calling (200) instead of (300). The (2000) routine at the end
+decrements .1, and I make calls to the addition and subtraction
+routines in the standard library.
+
+Two stacks are involved: the variable stack accessed by STASH and
+RETRIEVE, and the call stack accessed by NEXT and RESUME. The former
+is limited only by memory, but the latter is supposed to have a
+built-in limit of 80 pending returns. The tail-recursive routine has
+no problem with this. However, in order to permit the recursive
+routine (200) to run with amounts greater than 70, I had to remake the
+INTERCAL compiler with a larger limit.
+
+
+(To see this program compared with similar programs in other languages,
+visit http://www.webcom.com/nazgul/change.html.)
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