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 $A + B$.