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 (1.42.0) (judge verdict: Accepted)

use proconio::{input, fastout};

#[fastout]
fn main() {
    input! {
        s: String,
    };

    let numbers = s.chars().map(|n| n as i32 - 48).collect::<Vec<i32>>();

    for i in 0..(1usize << s.len()) {
        let mut ans = 0;
        for (j, num) in numbers.iter().enumerate() {
            if i & (1 << j) == 0 {
                ans -= num;
            } else {
                ans += num;
            }
        }
        if ans == 7 {
            for (j, num) in numbers.iter().enumerate() {
                print!("{}", num);
                if j == 3 {
                    continue;
                }
                if i & (1 << j+1) == 0 {
                    print!("-");
                } else {
                    print!("+");
                }
            }
            println!("=7");
            return ;
        }
    }
}