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 solver ()
  (let ((a (read)) (b (read)))
  (if (>= (+ a b) 10)
    (format t "error~%")
    (format t "~A~%" (+ a b)))))

(solver)