SUBROUTINE PARCLT(RL1,RL2,RM1,RM2,RN1,RN2)
      IF(RL1.LT.RM1)GO TO 10
      IF(RL1.GT.RM2)GO TO 20
      RN1=RL1
      IF(RL2-RM1)30,40,40
10    RN1=RM1
40    IF(RL2.LE.RM2)GO TO 50
      RN2=RM2
      GO TO 60
50    RN2=RL2
      GO TO 60
20    RN1=RM2
      IF(RL2.GE.RM1)GO TO 50
30    RN2=RM1
60    RETURN
      END