Problem:
Score : 100 points

Problem Statement

You are given positive integers A and B.

If A is a divisor of B, print A + B; otherwise, print B - A.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 20

Input

Input is given from Standard Input in the following format:

A B

Output

If A is a divisor of B, print A + B; otherwise, print B - A.

Sample Input 1

4 12

Sample Output 1

16

As 4 is a divisor of 12, 4 + 12 = 16 should be printed.

Sample Input 2

8 20

Sample Output 2

12

Sample Input 3

1 1

Sample Output 3

2

1 is a divisor of 1.

Solution in Ruby (2.3.3) (judge verdict: Runtime Error)

CostOf = [0,2,5,5,4,5,6,3,7,6]

N, M   = gets.split.map(&:to_i)
Digits = gets.split.map(&:to_i)

Lowest = Digits.min_by{|d| CostOf[d] }
Sorted = Digits.select{|d| Lowest < d }.sort_by{|d| -d } + Digits.select{|d| d < Lowest }.sort_by{|d| -CostOf[d]*10 - d }
FindFirstNums = lambda{|nums, remain|
	return nums if remain == 0
	(nums.empty? ? 0 : Sorted.index(nums.last)).upto(Sorted.length-1){|i|
		d = Sorted[i]
		if CostOf[d] <= remain + CostOf[Lowest]
			nums.push(d)
			return nums if FindFirstNums[nums, remain - CostOf[d] + CostOf[Lowest]]
			nums.pop
		end
	}
	return nil # never
}

nums = FindFirstNums[[], N % CostOf[Lowest]]
puts (nums + [Lowest] * (N / CostOf[Lowest] - nums.length)).sort.reverse.join('')