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 input::*;
use std::cmp::*;
use std::io::*;
use std::num::*;
use std::str::*;

mod input {
    use super::*;

    pub fn read<T: FromStr>() -> T {
        stdin()
            .bytes()
            .map(|c| c.unwrap() as char)
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>()
            .parse::<T>()
            .ok()
            .unwrap()
    }
    pub fn str() -> String {
        read()
    }
    pub fn s() -> Vec<char> {
        str().chars().collect()
    }
    pub fn i() -> i64 {
        read()
    }
    pub fn u() -> usize {
        read()
    }
    pub fn f() -> f64 {
        read()
    }
    pub fn c() -> char {
        read::<String>().pop().unwrap()
    }
    pub fn iv(n: usize) -> Vec<i64> {
        (0..n).map(|_| i()).collect()
    }
    pub fn uv(n: usize) -> Vec<usize> {
        (0..n).map(|_| u()).collect()
    }
    pub fn fv(n: usize) -> Vec<f64> {
        (0..n).map(|_| f()).collect()
    }
    pub fn cmap(h: usize) -> Vec<Vec<char>> {
        (0..h).map(|_| s()).collect()
    }
}

fn main() {
    let S = s();
    let S: Vec<i32> = S.iter().map(|c| *c as i32 - '0' as i32).collect();
    println!(
        "{}",
        if S[0] + S[1] + S[2] + S[3] == 7 {
            format!("{}+{}+{}+{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] + S[1] + S[2] - S[3] == 7 {
            format!("{}+{}+{}-{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] + S[1] - S[2] + S[3] == 7 {
            format!("{}+{}-{}+{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] + S[1] - S[2] - S[3] == 7 {
            format!("{}+{}-{}-{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] - S[1] + S[2] + S[3] == 7 {
            format!("{}-{}+{}+{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] - S[1] + S[2] - S[3] == 7 {
            format!("{}-{}+{}-{}=7", S[0], S[1], S[2], S[3])
        } else if S[0] - S[1] - S[2] + S[3] == 7 {
            format!("{}-{}-{}+{}=7", S[0], S[1], S[2], S[3])
        } else {
            format!("{}-{}-{}-{}=7", S[0], S[1], S[2], S[3])
        }
    )
}