@(define first_last (first last whole))
@  (all)
@(skip :greedy)@{last 1}
@  (and)
@{first 1}@(skip)
@  (and)
@whole
@  (end)
@(end)
@(next "amb/set1")
@(skip)
@(first_last fi1 la1 w1)
@(next "amb/set2")
@(skip)
@(first_last la1 la2 w2)
@(next "amb/set3")
@(skip)
@(first_last la2 la3 w3)
@(next "amb/set4")
@(skip)
@(first_last la3 la4 w4)
@(output)
@w1 @w2 @w3 @w4
@(end)