Problem:
Score : 100 points

Problem Statement

You are given two integers A and B as the input. Output the value of A + B.

However, if A + B is 10 or greater, output error instead.

Constraints

A and B are integers.

1 ≤ A, B ≤ 9

Input

Input is given from Standard Input in the following format:

A B

Output

If A + B is 10 or greater, print the string error (case-sensitive); otherwise, print the value of A + B.

Sample Input 1

6 3

Sample Output 1

9

Sample Input 2

6 4

Sample Output 2

error

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(defun split (string &key (delimiterp #'(lambda (c) (char= c #\Space))))
  (loop :for beg = (position-if-not delimiterp string)
        :then (position-if-not delimiterp string :start (1+ end))
        :for end = (and beg (position-if delimiterp string :start beg))
        :when beg :collect (subseq string beg end)
        :while end))

(destructuring-bind (a b) (mapcar #'parse-integer (split (read-line)))
  (let ((sum (+ a b)))
    (format t "~a~%" (if (>= sum 10)
                         "error"
                         sum))))