please can someone help me ? I have wrote this code and that dont work. I dont know what is bad.

```
public class Whileloop {

public static void main(String[] args) {
    // TODO Auto-generated method stub

    String equation ="+1x+1x+2=+1x+1x+6";
    String parts[] = equation.split("=");
    int no = 0;
    System.out.println(parts[no]);
    int helper = 5;
    for (parts[0].charAt(helper) != '-' || parts[0].charAt(helper) != '+';helper--) {
        System.out.println(helper);

    }
    System.out.println(helper);

  }
}

```

This is the result: 

```
+1x+1x+2
5
4
3
2
1
0

```

> 
> Exception in thread "main" java.lang.StringIndexOutOfBoundsException:
>  String index out of range: -1
>  at java.lang.String.charAt(Unknown Source)
>  at Whileloop.main(Whileloop.java:12)
> 
> 
>