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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)


#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
using namespace std;

#define rep(i,n)for(int i=0; i<(int)(n); i++)
#define bitrep(tmp, N)for (int tmp=0; tmp < (1<<N);tmp++)
#define all(v) v.begin(), end.bigin()

vector<int> inputs(4);
int n = 4;
string ans = "";

bool dfs(int i, string imme, int res){
  if (i==n){
    if (res==7){
      ans = imme+"=7";
      return true;  
    }else{
      return false;
    }
    
  }else{
    if(dfs(i+1, imme+"+"+to_string(inputs.at(i)), res+inputs.at(i))) return true;
    if(dfs(i+1, imme+"-"+to_string(inputs.at(i)), res-inputs.at(i))) return true;
  }
  return false;
}

int main(){
  
  rep(i,4) cin >> inputs.at(i);
  
  dfs(0, to_string(inputs.at(0)), inputs.at(0));
  cout << ans << endl;
}