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.List

main = do
  input <- map digitToInt <$> getLine
  let f = [(+), (-)]
      func = [[a, b, c] | a <- f, b <- f, c <- f]
      fS = ["+", "-"]
      funcS = [[a, b, c] | a <- fS, b <- fS, c <- fS]
      n = map show input
  putStrLn $ (\x -> toString n (funcS !! x)) . head . elemIndices 7 . map (solve input) $ func

solve :: [Int] -> [Int -> Int -> Int] -> Int
solve (n:ns) [] = n
solve (n:m:ms) (f:fs) = solve ((f n m):ms) fs

toString :: [String] -> [String] -> String
toString n f = (n!!0) ++ (f!!0) ++ (n!!1) ++ (f!!1) ++ (n!!2) ++ (f!!2) ++ (n!!3) ++ "=7"