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::*;
use std::str::FromStr;

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

const P: char = '+';
const M: char = '-';

fn main() {
    let s: Vec<i32> = read::<String>()
        .chars()
        .map(|c| c.to_digit(10).unwrap() as i32)
        .collect();

    let op: [[i32; 3]; 8] = [
        [0, 0, 0],
        [0, 0, 1],
        [0, 1, 0],
        [0, 1, 1],
        [1, 0, 0],
        [1, 0, 1],
        [1, 1, 0],
        [1, 1, 1],
    ];

    for i in 0..8 {
        let mut ans = s[0];
        if op[i][0] == 0 { ans += s[1]; } else { ans -= s[1]; }
        if op[i][1] == 0 { ans += s[2]; } else { ans -= s[2]; }
        if op[i][2] == 0 { ans += s[3]; } else { ans -= s[3]; }
        if ans == 7 {
            println!("{}{}{}{}{}{}{}=7",
                     s[0],
                     if op[i][0] == 0 { P } else { M },
                     s[1],
                     if op[i][1] == 0 { P } else { M },
                     s[2],
                     if op[i][2] == 0 { P } else { M },
                     s[3]);
            break;
        }
    }

}