Problem:
Score : 300 points

Problem Statement

Sitting in a station waiting room, Joisino is gazing at her train ticket.

The ticket is numbered with four digits A, B, C and D in this order, each between 0 and 9 (inclusive).

In the formula A op1 B op2 C op3 D = 7, replace each of the symbols op1, op2 and op3 with + or - so that the formula holds.

The given input guarantees that there is a solution. If there are multiple solutions, any of them will be accepted.

Constraints

0≤A,B,C,D≤9

All input values are integers.

It is guaranteed that there is a solution.

Input

Input is given from Standard Input in the following format:

ABCD

Output

Print the formula you made, including the part =7.

Use the signs + and -.

Do not print a space between a digit and a sign.

Sample Input 1

1222

Sample Output 1

1+2+2+2=7

This is the only valid solution.

Sample Input 2

0290

Sample Output 2

0-2+9+0=7

0 - 2 + 9 - 0 = 7 is also a valid solution.

Sample Input 3

3242

Sample Output 3

3+2+4-2=7

Solution in Ruby (2.3.3) (judge verdict: Accepted)

def add_or_subtract(numbers, n)
  if numbers.length == 1
    if numbers[0] == n
      return numbers[0].to_s
    else
      return false
    end
  end
    last = numbers[-1]
    candidate1 = add_or_subtract(numbers[0..(numbers.length - 2)], n - last)
    candidate2 = add_or_subtract(numbers[0..(numbers.length - 2)], n + last)
    if candidate1
      return candidate1 + "+#{last.to_s}"
    elsif candidate2
      return candidate2 + "-#{last.to_s}"
    else
      return false
    end
end

numbers = gets.chomp.split("").map(&:to_i)
puts add_or_subtract(numbers, 7) + "=7"