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 Python (3.4.3) (judge verdict: Accepted)

from collections import defaultdict,deque
import sys,heapq,bisect,math,itertools,string,queue,copy,time
import numpy as np
sys.setrecursionlimit(10**8)
INF = float('inf')
mod = 10**9+7
eps = 10**-7
def inp(): return int(sys.stdin.readline())
def inpl(): return list(map(int, sys.stdin.readline().split()))
def inpl_str(): return list(sys.stdin.readline().split())

ans = 0
S = input()
n = len(S)
def dfs(i, ans_string, tot):
    if i == n-1:
        if tot == 7: 
            print(ans_string+"=7") 
            return True 
        else: return False
    return dfs(i+1, ans_string +"+" + S[i+1], tot + int(S[i+1])) \
     or dfs(i+1, ans_string + "-" + S[i+1], tot-int(S[i+1]))

dfs(0,S[0],int(S[0]))