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::collections::HashMap;
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

fn read_vec2<T: std::str::FromStr>(n: u32) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}
fn main(){
    let (a,b,c,d) = {
        let t:Vec<i64> =read::<String>().chars().map(|x|  x.to_digit(10).unwrap() as i64).collect();
        (t[0],t[1],t[2],t[3])
    };
    if a + b + c + d == 7 { println!("{}+{}+{}+{}=7",a,b,c,d); return;}
    if a + b + c - d == 7 { println!("{}+{}+{}-{}=7",a,b,c,d); return;}
    if a + b - c + d == 7 { println!("{}+{}-{}+{}=7",a,b,c,d); return;}
    if a + b - c - d == 7 { println!("{}+{}-{}-{}=7",a,b,c,d); return;}
    if a - b - c - d == 7 { println!("{}-{}-{}-{}=7",a,b,c,d); return;}
    if a - b - c + d == 7 { println!("{}-{}-{}+{}=7",a,b,c,d); return;}
    if a - b + c - d == 7 { println!("{}-{}+{}-{}=7",a,b,c,d); return;}
    if a - b + c + d == 7 { println!("{}-{}+{}+{}=7",a,b,c,d); return;}
}