(define prgs
'(
   ( 
      (procedure start
         (turn-right (if wall? (turn-left 
             (if wall? (turn-left (if wall? (turn-left (if wall? (turn-left (if wall? turn-left step)) step)) step)) step)) step)
                 put-mark start )
      )   
      (procedure turn-right (turn-left turn-left turn-left turn-left turn-left))
  )
)
)


(define pairs
'(
  (
   (((w w w w w w) 
      (w 0 0 0 0 w) 
     (w 1 w 0 0 w) 
      (w 1 0 0 0 w) 
     (w w w w w w)) 
     (1 3) southeast)

   (((w w w w w w) 
      (w 0 0 0 0 w) 
     (w 0 w 0 0 w) 
      (w 0 0 0 0 w) 
     (w w w w w w)) 
     (1 1) northeast)
   )
   (
   (((w w w w w w) 
      (w 0 0 0 0 w) 
     (w 0 0 2 0 w) 
      (w 1 3 0 0 w) 
     (w w w w w w)) 
     (3 3) northwest)

   (((w w w w w w) 
      (w 0 0 0 0 w) 
     (w 0 0 0 0 w) 
      (w 0 0 0 0 w) 
     (w w w w w w)) 
     (1 1) northwest)
  ))
 )

(newline) 
(evaluate prgs pairs '(10 10 10 10) 5)