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)

#[macro_use]
pub mod basic_stdin {
use std::str::FromStr;

pub fn read<T: FromStr>() -> T {
    use std::io::stdin;
    use std::io::Read;

    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed reading char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed parsing")
}

}

#[macro_export]
macro_rules! test_function {
    (func = $func:expr, $($input:expr => $output:expr),* $(,)*) => {
        $(
            assert_eq!($func(std::io::Cursor::new($input)) , $output);
        )*
    };
}

#[macro_export]
macro_rules! input_macro {
    (string = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    (reader = $s:expr, $($r:tt)*) => {
        let reader = std::io::BufReader::new($s);
        let mut bytes = std::io::Read::bytes(reader);
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    let stdin = std::io::stdin();
    let ret = solve(stdin.lock());

    println!("{}", ret);
}

fn f(vec: &Vec<i32>, op1: i32, op2: i32, op3: i32) -> i32 {
    let mut ret;
    let a = vec[0];
    let b = vec[1];
    let c = vec[2];
    let d = vec[3];

    if op1 == 0 {
        ret = a + b;
    } else {
        ret = a - b;
    }

    if op2 == 0 {
        ret += c;
    } else {
        ret -= c;
    }

    if op3 == 0 {
        ret += d;
    } else {
        ret -= d;
    }

    ret
}
use std::fmt::format;

fn solve<T: std::io::Read>(reader: T) -> String {
    input_macro! {
        reader = reader,
        s: String,
    }

    let vec: Vec<i32> = s.chars().map(|b| b as i32 - '0' as i32).collect();

    for op1 in 0..2 {
        for op2 in 0..2 {
            for op3 in 0..2 {
                if f(&vec, op1, op2, op3) == 7 {
                    let a = vec[0];
                    let b = vec[1];
                    let c = vec[2];
                    let d = vec[3];

                    let c1 = if op1 == 0 { "+" } else { "-" };
                    let c2 = if op2 == 0 { "+" } else { "-" };
                    let c3 = if op3 == 0 { "+" } else { "-" };

                    let ret = format!("{}{}{}{}{}{}{}=7", a, c1, b, c2, c, c3, d);
                    return ret;
                }
            }
        }
    }

    assert!(false);
    "".to_string()
}

#[cfg(test)]
mod tests {

    #[test]
    fn test_solve_function() {
        atcorder::test_function! {
            func = super::solve,
            "1222" => "1+2+2+2=7",
        }
    }
}