Javascript - unselect checkboxes, items mutually exclusive

I have a group of check boxes that are all part of one array. What I require is that if the first one is selected (I don't mind), then any of the others are unselected, and vice versa - if one of the bottom three options are selected, then I don't mind needs to be unselected. The last three options can all be selected at the same time.

This Link is similar to what I am asking to do. Any help would be appreciated

<fieldset class="checkbox">
    <legend>Sitter type</legend>
    <div id="field_844" class="input-options checkbox-options">
        <label for="field_1071_0" class="option-label">
            <input  type="checkbox" name="field_844[]" id="field_1071_0" value="I don&#039;t mind">I don&#039;t mind</label>
        <label for="field_1072_1" class="option-label">
            <input  checked="checked" type="checkbox" name="field_844[]" id="field_1072_1" value="Sitter">Sitter</label>
        <label for="field_1073_2" class="option-label">
            <input  type="checkbox" name="field_844[]" id="field_1073_2" value="Nanny">Nanny</label>
        <label for="field_1074_3" class="option-label">
            <input  type="checkbox" name="field_844[]" id="field_1074_3" value="Au Pair">Au Pair</label>
    </div>
</fieldset>