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;
using static System.Console;

class Program
{
    static void Main(string[] args)
    {
        new Program().Calc();
    }

    Scanner cin;

    public Program() { }

    bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (b.CompareTo(a) < 0) { a = b; return true; } return false; }

    void Calc()
    {
        cin = new Scanner();

        string str = ReadLine();
        int A = int.Parse(str[0].ToString());
        int B = int.Parse(str[1].ToString());
        int C = int.Parse(str[2].ToString());
        int D = int.Parse(str[3].ToString());

        int ans = 0;

        if (A+B+C+D == 7) { ans = 0; }
        else if (A-B+C+D == 7) { ans = 1; }
        else if (A+B-C+D == 7) { ans = 2; }
        else if (A-B-C+D == 7) { ans = 3; }
        else if (A+B+C-D == 7) { ans = 4; }
        else if (A-B+C-D == 7) { ans = 5; }
        else if (A+B-C-D == 7) { ans = 6; }
        else if (A-B-C-D == 7) { ans = 7; }

        bool op1 = (ans & 1) == 1;
        bool op2 = (ans & 2) == 2;
        bool op3 = (ans & 4) == 4;

        String ansStr = A.ToString() + (op1 ? "-" : "+") + B.ToString() + (op2 ? "-" : "+")
            + C.ToString() + (op3 ? "-" : "+") + D.ToString() + "=7";

        WriteLine(ansStr);
    }
}

public static class StringExtension
{
    public static char GetChar1(this string str, int indexOneBase)
    {
        return str[indexOneBase - 1];
    }
}

class Scanner
{
    string[] s;
    int i;

    char[] cs = new char[] { ' ' };

    public Scanner()
    {
        s = new string[0];
        i = 0;
    }

    public string next()
    {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        if (s.Length == 0) return next();
        i = 0;
        return s[i++];
    }

    public int nextInt()
    {
        return int.Parse(next());
    }
    public int[] ArrayInt(int N, int add = 0)
    {
        int[] Array = new int[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextInt() + add;
        }
        return Array;
    }

    public long nextLong()
    {
        return long.Parse(next());
    }

    public long[] ArrayLong(int N, long add = 0)
    {
        long[] Array = new long[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextLong() + add;
        }
        return Array;
    }

    public double nextDouble()
    {
        return double.Parse(next());
    }


    public double[] ArrayDouble(int N, double add = 0)
    {
        double[] Array = new double[N];
        for (int i = 0; i < N; i++)
        {
            Array[i] = nextDouble() + add;
        }
        return Array;
    }
}