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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class AtCoder
{
  public static void Main()
  {
    var abcd = Console.ReadLine().Trim().ToCharArray().Select(e => int.Parse(e.ToString())).ToArray();
    var a = abcd[0];
    var b = abcd[1];
    var c = abcd[2];
    var d = abcd[3];

    var n = Math.Pow(2, 3);
    var op = new int[3];

    var ans = "";

    for(var i=0; i < n; i++)
    {
      op[0] = ((i >> 0) & 1) > 0 ? 1 : -1;
      op[1] = ((i >> 1) & 1) > 0 ? 1 : -1;
      op[2] = ((i >> 2) & 1) > 0 ? 1 : -1;

      var v = a
       + b * op[0]
       + c * op[1]
       + d * op[2];

       if(v == 7) break;
    } 

    var k = new []{ "-", "", "+"};

    Console.WriteLine(a + k[op[0]+1] + b + k[op[1]+1] + c+ k[op[2]+1] + d + "=7");
  }
}