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: Runtime Error)

sealed abstract class Operand

case object Plus extends Operand

case object Minus extends Operand

object Main extends App {
  val N = io.StdIn.readLine().split("").map(_.toInt)

  def calc(o: List[Operand], index: Int, calculated: Int): (Boolean, List[Operand]) = {
    if (index == 3) {
      if (calculated == 7) (true, o) else (false, o)
    }
    else {
      val p = calc(Plus :: o, index + 1, calculated + N(index + 1))
      val m = calc(Minus :: o, index + 1, calculated - N(index + 1))
      if (p._1) p else m
    }
  }

  def printExp(o: List[Operand]): Unit = {
    for (i <- 0 to 2) {
      o(i) match {
        case Plus => print(s"${N(i)}+")
        case Minus => print(s"${N(i)}-")
      }
    }
    println(s"${N(3)}=7")
  }

  val calculated = calc(List(), 0, N.head)
  printExp(calculated._2.reverse)
}