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.Maybe

main :: IO ()
main = do
    digits <- map (read . return) <$> getLine :: IO [Int]
    putStrLn . (++"=7") . tail . fromJust $ genFormula 0 "" digits

genFormula :: Int -> String -> [Int] -> Maybe String
genFormula n s [] = if n == 7 then Just s else Nothing
genFormula n s (x:xs) = let
    a = genFormula (n+x) (s++"+"++show x) xs
    b = genFormula (n-x) (s++"-"++show x) xs
    in case (isJust a, isJust b) of
        (True  ,    _) -> a
        (_     , True) -> b
        (False, False) -> Nothing