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)

def f(h, a, b)
  base = b
  optional = a-b
  (1..h.max).bsearch{|i|
    cnt = 0
    h.map{|hp|
      cnt += ([hp - base * i, 0].max.fdiv(optional)).ceil
#      break if cnt > i
    }
    cnt <= i
  }
end

N, A, B = gets.split.map(&:to_i)
H = N.times.map{gets.to_i}

p f(H, A, B)