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.

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.

Constraints

• A and B are integers.
• 1 ≤ A, B ≤ 9

Sample Input 1

6 3

Sample Output 1

9

Sample Input 2

6 4

Sample Output 2

error

见题面 Input 部分

见题面 Output 部分