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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC079C
{
    class Program
    {
        static readonly int answer = 7;

        static string solve(List<int> nums, int index, int current, string op, List<string> ops)
        {
            ops.Add(op);

            //Console.WriteLine($"{index}, {current}, {op}");
            if (index >= nums.Count())
            {
                if (current == answer)
                {
                    var sb = new StringBuilder();
                    foreach (var i in Enumerable.Range(0, nums.Count() - 1))
                    {
                        sb.Append(nums[i]);
                        sb.Append(ops[i + 2]);
                    }
                    sb.Append(nums[nums.Count() - 1]);
                    sb.AppendFormat("={0}", answer);

                    return sb.ToString();
                }
                else
                {
                    return "";
                }
            }

            var s = solve(nums, index + 1, current + nums[index], "+", new List<string>(ops));
            if (string.IsNullOrEmpty(s))
            {
                s = solve(nums, index + 1, current - nums[index], "-", new List<string>(ops));
            }

            return s;
        }

        static void Main(string[] args)
        {
            var nums = Console.ReadLine().Select(x => int.Parse(new string(x, 1))).ToList();

            var expr = solve(nums, 0, 0, "+", new List<string>());
            Console.WriteLine(expr);
        }
    }
}