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)

extern crate core;

use std::io::{self, Read};

fn main() {
    let mut input = String::new();
    io::stdin().read_to_string(&mut input).unwrap();
    let output = run(input.trim().to_string());
    println!("{}", output);
}

fn run(input: String) -> String {
    let list = input
        .chars()
        .map(|x| x.to_string().parse::<i32>().unwrap())
        .collect::<Vec<_>>();
    // 総当たり
    for i in 0..1 << 4 {
        let ap = i & 0b1000 == 0;
        let bp = i & 0b0100 == 0;
        let cp = i & 0b0010 == 0;
        let dp = i & 0b0001 == 0;

        let a = if ap { list[0] } else { -list[0] };
        let b = if bp { list[1] } else { -list[1] };
        let c = if cp { list[2] } else { -list[2] };
        let d = if dp { list[3] } else { -list[3] };

        if a + b + c + d == 7 && ap {
            return format!(
                "{}{}{}{}{}{}{}=7",
                list[0],
                if bp { "+" } else { "-" },
                list[1],
                if cp { "+" } else { "-" },
                list[2],
                if dp { "+" } else { "-" },
                list[3]
            ).to_string();
        }
    }
    panic!("");
}

#[test]
fn test() {
    let tests = vec![("1222", "1+2+2+2=7"), ("0290", "0-2+9+0=7")];
    for (i, (input, output)) in tests.into_iter().enumerate() {
        println!("test:{}", i);
        assert_eq!(run(input.to_string()), output.to_string());
    }
}