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)

io = STDIN
n=io.gets.chomp.to_i
s=[]
n.times do
  s<<io.gets.chomp.to_i
end
ss=s.sort.select{|i|i%10!=0}
if ss==[]
  puts 0
else
  sum=s.inject(:+)
  ss.each do |i|
    break if sum%10 != 0
    sum-=i
  end
  puts sum
end