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)

// This code is generated by [cargo-atcoder](https://github.com/tanakh/cargo-atcoder)
// Original source code:
/*
#[allow(unused_imports)]
use itertools::*;
#[allow(unused_imports)]
use proconio::marker::*;
#[allow(unused_imports)]
use proconio::*;
use std::char;
#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
#[allow(unused_imports)]
use std::f64::consts::*;
fn main() {
    input! {
        s: Chars,
    }

    let nums: Vec<i32> = s
        .into_iter()
        .map(|c| c.to_digit(10).unwrap() as i32)
        .collect();

    for i in 0..2i32.pow(3) {
        if calc(&nums, i) == 7 {
            print_format(&nums, i);
            return;
        }
    }
}

fn print_format(nums: &Vec<i32>, op: i32) {
    let mut s = vec![char::from_digit(nums[0] as u32, 10).unwrap()];

    for i in 0usize..3 {
        if op / 2i32.pow(i as u32) % 2 == 0 {
            s.push('-');
        } else {
            s.push('+');
        }
        s.push(char::from_digit(nums[i + 1] as u32, 10).unwrap());
    }
    println!("{}={}", s.into_iter().collect::<String>(), calc(nums, op));
}

fn calc(nums: &Vec<i32>, op: i32) -> i32 {
    let mut total = nums[0];

    for i in 0usize..3 {
        // eprint!("i:{}, ", i);
        let o = op / 2i32.pow(i as u32) % 2;
        // eprintln!("o:{}", o);
        total += nums[i + 1] * (2 * o - 1);
    }

    return total;
}
*/

fn main() {
    let exe = "/tmp/binD28AB320";
    std::io::Write::write_all(&mut std::fs::File::create(exe).unwrap(), &decode(BIN)).unwrap();
    std::fs::set_permissions(exe, std::os::unix::fs::PermissionsExt::from_mode(0o755)).unwrap();
    std::process::exit(std::process::Command::new(exe).status().unwrap().code().unwrap())
}

fn decode(v: &str) -> Vec<u8> {
    let mut ret = vec![];
    let mut buf = 0;
    let mut tbl = vec![64; 256];
    for i in 0..64 { tbl[TBL[i] as usize] = i as u8; }
    for (i, c) in v.bytes().filter_map(|c| { let c = tbl[c as usize]; if c < 64 { Some(c) } else { None } }).enumerate() {
        match i % 4 {
            0 => buf = c << 2,
            1 => { ret.push(buf | c >> 4); buf = c << 4; }
            2 => { ret.push(buf | c >> 2); buf = c << 6; }
            3 => ret.push(buf | c),
            _ => unreachable!(),
        }
    }
    ret
}

const TBL: &'static [u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const BIN: &'static str = "<base64-encoded ELF executable removed>";