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: Wrong Answer)

use std::io;


fn main() {
    let abcd = read_one::<String>().chars()
        .map(|c| c as isize - '0' as isize)
        .collect::<Vec<isize>>();

    // 0: +, 1: -
    for j in 0..1 << (abcd.len() - 1) {
        let mut sum = abcd[0];
        let mut ans = abcd[0].to_string();
        for k in 1..abcd.len() {
            if (j & 1 << k) == 0 {
                sum += abcd[k];
                ans.push_str(format!("+{}", abcd[k]).as_str());
            } else {
                sum -= abcd[k];
                ans.push_str(format!("-{}", abcd[k]).as_str());
            }
        }

        if sum == 7 {
            println!("{}=7", ans);
            return;
        }
    }
}


#[allow(dead_code)]
fn read<T>() -> Vec<T>
where T:
    std::str::FromStr,
    T::Err: std::fmt::Debug {

    let mut buf = String::new();
    io::stdin().read_line(&mut buf).unwrap();
    buf.split_whitespace()
        .map(|s| s.trim().parse().unwrap())
        .collect()
}

#[allow(dead_code)]
fn read_one<T>() -> T
where T:
    std::str::FromStr,
    T::Err: std::fmt::Debug {

    let mut buf = String::new();
    io::stdin().read_line(&mut buf).unwrap();
    buf.trim().parse().unwrap()
}