Task

Write a program that solves the odd word problem with the restrictions given below.



Description

You are promised an input stream consisting of English letters and punctuations.

It is guaranteed that:

 the words (sequence of consecutive letters) are delimited by one and only one punctuation,
 the stream will begin with a word,
 the words will be at least one letter long,   and 
 a full stop (a period, [.]) appears after, and only after, the last word.


Example

A stream with six words:

 what,is,the;meaning,of:life. 


The task is to reverse the letters in every other word while leaving punctuations intact, producing:

 what,si,the;gninaem,of:efil. 
while observing the following restrictions:

 Only I/O allowed is reading or writing one character at a time, which means: no reading in a string, no peeking ahead, no pushing characters back into the stream, and no storing characters in a global variable for later use;
 You are not to explicitly save characters in a collection data structure, such as arrays, strings, hash tables, etc, for later reversal;
 You are allowed to use recursions, closures, continuations, threads, co-routines, etc., even if their use implies the storage of multiple characters.


Test cases

Work on both the   "life"   example given above, and also the text:

 we,are;not,in,kansas;any,more.


func rev {
    (var c = STDIN.getc) \\ return()
    if (c ~~ /^[a-z]\z/i) {
        var r = rev()
        print c
        return r
    }
    return c
}
 
var (n=0, l=false)
while (defined(var c = STDIN.getc)) {
    var w = (c ~~ /^[a-z]\z/i)
    ++n if (w && !l)
    l = w
    if (n & 1) {
        print c
    } else {
        var r = rev()
        print(c, r)
        n = 0
        l = false
    }
}