PROC r = (INT k, PROC INT r1, r2)VOID:
  IF k>0 THEN
    INT a := 0;
    r(k-1, INT: (a := (a*23 + 3) MOD 1000; a), r1)
  ELSE
    INT n := 0;
    TO 3 DO print(r1) OD; print(newline);
    TO 3 DO print(r2) OD; print(newline);
    r2; # give it a head start. #
    WHILE r1 NE r2 DO n +:= 1; r2 OD;
    print(n)
FI;

r(2, SKIP, SKIP)