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)

#![allow(unused_imports, unused_variables, unused_macros, unused_mut, dead_code)]
use std::io::*;
use std::str::FromStr;

fn read_line<T: FromStr>(stdin_lock: &mut StdinLock) -> T {
    let mut line: String = String::new();
    stdin_lock.read_line(&mut line).expect("input error");
    line.trim().to_string().parse().ok().expect("parse error")
}

fn sep_line<T: FromStr>(stdin_lock: &mut StdinLock, sep: char) -> Vec<T> {
    let mut line: String = String::new();
    stdin_lock.read_line(&mut line).expect("input error");
    line = line.trim().to_string();
    let res: Vec<&str> = line.split(sep).collect();
    res.iter().map(|s| s.to_string().parse::<T>()
                   .ok().expect("parse error")).collect()
}

fn main() {
    let stdin = stdin();
    let mut stdin_lock = stdin.lock();
    let d:Vec<i32> = read_line::<String>(&mut stdin_lock).chars()
        .map(|c| c as i32 - '0' as i32).collect();
    let n = d.len();
    for i in 0..(1<<(n-1)) {
        let mut p = vec![' '];
        let mut x: i32 = d[0];
        for j in 0..(n-1) {
            if (i & (1<<j)) != 0 {
                x += d[j+1];
                p.push('+');
            } else {
                x -= d[j+1];
                p.push('-');
            }
        }
        if x == 7 {
            print!("{}", d[0]);
            for j in 1..d.len() {
                print!("{}{}", p[j], d[j]);
            }
            println!("=7");
            break;
        }
    }
}