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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::Read;

fn main() {
    let mut buf = String::new();

    // 標準入力から全部bufに読み込む
    std::io::stdin().read_to_string(&mut buf).unwrap();
    let mut iter = buf.split_whitespace();
    let s: String = iter.next().unwrap().parse().unwrap();

    let numbers: Vec<i32> = s.chars().map(|x| x.to_digit(10).unwrap() as i32).collect();
    let operands: Vec<i32> = numbers[1..].to_vec();
    let mut results: Vec<Vec<i32>> = Vec::new();

    for i in 0..8 {
        let mut row = numbers[1..].to_vec();
        for j in 0..i {
            if ((i >> j) & 1) == 1 {
                row[j] = -operands[j];
            }
        }
        results.push(row);
    }

    for result in results {
        if result.iter().fold(0, |acc, num| acc + num) + numbers[0] == 7 {
            let formula = result
                .iter()
                .map(|num| {
                    if *num < 0 {
                        num.to_string()
                    } else {
                        format!("{}{}", "+", num.to_string())
                    }
                })
                .collect::<Vec<String>>()
                .join("");
            println!("{}{}=7", numbers[0], formula);
            return;
        }
    }
}