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 ConsoleApp15
{
    class Class132
    {
        static void Main()
        {
            string ABCD = Console.ReadLine();
            int ans = -1;
            for(int i = 0; i < (1 << ABCD.Length - 1); i++)
            {
                int sum = int.Parse(ABCD[0].ToString());
                for(int j = 1; j < ABCD.Length; j++)
                {
                    if ((i & (1 << j - 1)) > 0)
                    {
                        sum += int.Parse(ABCD[j].ToString());
                    }
                    else
                    {
                        sum -= int.Parse(ABCD[j].ToString());
                    }
                }
                if (sum == 7)
                {
                    ans = i;break;
                }
            }
            if (ans >= 0)
            {
                string show = ABCD[0].ToString();
                for(int i = 0; i < ABCD.Length - 1; i++)
                {
                    if ((ans & (1 << i)) > 0) show += "+";
                    else show += "-";
                    show += ABCD[i + 1];
                }
                show += "=7";
                Console.WriteLine(show);
            }
        }
    }
}