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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Data.Char
import Data.Bits

printWithSign :: Int -> String
printWithSign x
    | x >= 0 = "+" ++ show x
    | x < 0 = show x

solve :: [Int] -> Int -> [[Int]]
solve xs i = [l | j <- [0..i], let l = loop xs j, sum l == 7]
    where
        loop :: [Int] -> Int -> [Int]
        loop [x] _ = [x]
        loop (x:y:xs) i
            | i .&. 1 == 1 = x : loop (y:xs) (shiftR i 1)
            | otherwise = x : loop (negate y:xs) (shiftR i 1)

main = do
    xs <- map digitToInt <$> getLine :: IO [Int]
    let [a,b,c,d] = head $ solve xs (2^(length xs - 1) - 1)
    putStr $ show a
    putStr $ printWithSign b
    putStr $ printWithSign c
    putStr $ printWithSign d
    putStrLn  "=7"