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 Ruby (2.3.3) (judge verdict: Runtime Error)

a,b,c,d = gets.split.map(&:to_i)

start = a < c ? c : a
finish = b < d ? b : d

result = finish - start < 0 ? 0 : finish-start

puts result