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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

string s;
string ans;

void Backtrack(int i, int total) {
    if (i==4) {
        if (total==7) {
            for (int j=0; j<ans.size(); ++j) {
                cout << ans[j];
            }

            cout << "=7";

            exit(0);
        }
        else {
            return;
        }
    }


    total+=(s[i]-'0');
    ans+='+';
    ans+=s[i];
    Backtrack(i+1, total);
    total-=(s[i]-'0');
    ans.pop_back();
    ans.pop_back();

    total-=(s[i]-'0');
    ans+='-';
    ans+=s[i];
    Backtrack(i+1, total);
    total+=(s[i]-'0');
    ans.pop_back();
    ans.pop_back();
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> s;
    ans+=s[0];
    Backtrack(1, s[0]-'0');

    return 0;
}