DO
   INPUT PROMPT "Enter two integers separated by a comma: ": A, B
   IF ABS(A)>1000 OR ABS(B)>1000 OR IP(A)<>A OR IP(B)<>B THEN
      PRINT "Both integers must be in the interval [-1000..1000] - try again."
      PRINT
   ELSE
      PRINT "Their sum is";A+B
      EXIT DO
   END IF
LOOP
END