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 std::io;

fn read_line() -> Vec<i32> {
    let mut line = String::new();
    let mut inputs = Vec::<i32>::new();
    io::stdin().read_line(&mut line).unwrap();
    // let inputs = line.trim().chars().map(|x| x.parse::<i32>().unwrap());
    let inputs = line.trim().chars().map(|x| x.to_digit(10).unwrap() as i32);
    inputs.collect::<Vec<i32>>()
}

fn operation(op: &char, l_operand: &i32, r_operand: i32) -> i32 {
    if *op == '+' {
        return l_operand + r_operand;
    } else if *op == '-' {
        return l_operand - r_operand;
    } else {
        panic!("");
    }
}

fn solve(a: i32, b: i32, c: i32, d: i32) {
    let op_list = vec!['+', '-'];
    for op1 in op_list.iter() {
        let mut res = operation(op1, &a, b);
        for op2 in op_list.iter() {
            let res2 = operation(op2, &res, c);
            for op3 in op_list.iter() {
                let res3 = operation(op3, &res2, d);
                if res3 == 7 {
                    println!("{}{}{}{}{}{}{}=7", a, op1, b, op2, c, op3, d);
                    return;
                }
            }
        }
    }
}

fn main() {
    let inputs = read_line();
    solve(inputs[0], inputs[1], inputs[2], inputs[3]);
}