<p>You are given a <b>0-index</b><strong>ed</strong> string <code>street</code>. Each character in <code>street</code> is either <code>&#39;H&#39;</code> representing a house or <code>&#39;.&#39;</code> representing an empty space.</p>

<p>You can place buckets on the <strong>empty spaces</strong> to collect rainwater that falls from the adjacent houses. The rainwater from a house at index <code>i</code> is collected if a bucket is placed at index <code>i - 1</code> <strong>and/or</strong> index <code>i + 1</code>. A single bucket, if placed adjacent to two houses, can collect the rainwater from <strong>both</strong> houses.</p>

<p>Return <em>the <strong>minimum </strong>number of buckets needed so that for <strong>every</strong> house, there is <strong>at least</strong> one bucket collecting rainwater from it, or </em><code>-1</code><em> if it is impossible.</em></p>

<p>&nbsp;</p>
<p><strong>Example 1:</strong></p>

<pre>
<strong>Input:</strong> street = &quot;H..H&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong>
We can put buckets at index 1 and index 2.
&quot;H..H&quot; -&gt; &quot;HBBH&quot; (&#39;B&#39; denotes where a bucket is placed).
The house at index 0 has a bucket to its right, and the house at index 3 has a bucket to its left.
Thus, for every house, there is at least one bucket collecting rainwater from it.
</pre>

<p><strong>Example 2:</strong></p>

<pre>
<strong>Input:</strong> street = &quot;.H.H.&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong>
We can put a bucket at index 2.
&quot;.H.H.&quot; -&gt; &quot;.HBH.&quot; (&#39;B&#39; denotes where a bucket is placed).
The house at index 1 has a bucket to its right, and the house at index 3 has a bucket to its left.
Thus, for every house, there is at least one bucket collecting rainwater from it.
</pre>

<p><strong>Example 3:</strong></p>

<pre>
<strong>Input:</strong> street = &quot;.HHH.&quot;
<strong>Output:</strong> -1
<strong>Explanation:</strong>
There is no empty space to place a bucket to collect the rainwater from the house at index 2.
Thus, it is impossible to collect the rainwater from all the houses.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= street.length &lt;= 10<sup>5</sup></code></li>
	<li><code>street[i]</code> is either<code>&#39;H&#39;</code> or <code>&#39;.&#39;</code>.</li>
</ul>