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::prelude::*;

fn input<T>() -> T
where
    T: std::str::FromStr,
{
    let stdin = std::io::stdin();
    let token: String = stdin
        .lock()
        .bytes()
        .map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().unwrap()
}

fn main() {
    let s: Vec<char> = input::<String>().chars().collect();
    let a = (s[0] as u8 - '0' as u8) as i32;
    let b = (s[1] as u8 - '0' as u8) as i32;
    let c = (s[2] as u8 - '0' as u8) as i32;
    let d = (s[3] as u8 - '0' as u8) as i32;

    let mut ans = (0, 0, 0);
    for &i in &[0, 1] {
        for &j in &[0, 1] {
            for &k in &[0, 1] {
                let mut temp = a;
                if i == 0 {
                    temp += b;
                } else {
                    temp -= b;
                }
                if j == 0 {
                    temp += c;
                } else {
                    temp -= c;
                }
                if k == 0 {
                    temp += d;
                } else {
                    temp -= d;
                }

                if temp == 7 {
                    ans = (i, j, k);
                }
            }
        }
    }

    println!(
        "{}{}{}{}{}{}{}=7",
        a,
        if ans.0 == 0 { '+' } else { '-' },
        b,
        if ans.1 == 0 { '+' } else { '-' },
        c,
        if ans.2 == 0 { '+' } else { '-' },
        d
    );
}