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 input<T:FromStr>() -> T {
  let mut line: String = String::new();
  io::stdin().read_line(&mut line);
  line.trim().parse().ok().unwrap()
}

fn dfs(i: i32, nums: &Vec<i32>, sum: i32, opes: &mut Vec<String>) -> bool {
  if i == nums.len() as i32{
    if sum == 7 {
      println!("{}{}{}{}{}{}{}=7", nums[0], opes[1], nums[1], opes[2], nums[2], opes[3], nums[3]);
      return true;
    } else {
      return false;
    }
  }
  opes[i as usize] = String::from("+");
  if dfs(i+1, nums, sum + nums[i as usize], opes){
    return true;
  }
  opes[i as usize] = String::from("-");
  if dfs(i+1, nums, sum - nums[i as usize], opes) {
    return true;
  }
  return false;
}

fn main() {
  let s: String = input();
  let mut nums: Vec<i32> = Vec::new();
  for c in s.chars() {
    nums.push(c as i32 - 48);
  }

  dfs(1, &nums, nums[0], &mut vec![String::from(""); 4]);

}