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 Scala (2.11.7) (judge verdict: Accepted)

import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)

  val x = sc.nextInt

  val d = x % 10
  val c = x % 100 / 10
  val b = x % 1000 / 100
  val a = x / 1000

  val bins = (0 until 8).map(k => zeroEmbeddingtoString(k.toBinaryString, 3))

  val res = bins.find { bin =>
    a + (if (bin(0) == '0') 1 else -1) * b +(if (bin(1) == '0') 1 else -1) * c +(if (bin(2) == '0') 1 else -1) * d == 7
  }.fold("impossible") { bin =>
    val flg0 = if (bin(0) == '0') "+" else "-"
    val flg1 = if (bin(1) == '0') "+" else "-"
    val flg2 = if (bin(2) == '0') "+" else "-"
    s"$a$flg0$b$flg1$c$flg2$d=7"
  }

  println(res)

  def zeroEmbeddingtoString(str: String, index: Int): String ={
    val l = str.length
    List.fill(index - l)("0").mkString + str
  }

}