<p>You are given a <strong>0-indexed</strong> 2D integer array <code>grid</code> of size <code>m x n</code> which represents a field. Each cell has one of three values:</p>
<ul>
<li><code>0</code> represents grass,</li>
<li><code>1</code> represents fire,</li>
<li><code>2</code> represents a wall that you and fire cannot pass through.</li>
</ul>
<p>You are situated in the top-left cell, <code>(0, 0)</code>, and you want to travel to the safehouse at the bottom-right cell, <code>(m - 1, n - 1)</code>. Every minute, you may move to an <strong>adjacent</strong> grass cell. <strong>After</strong> your move, every fire cell will spread to all <strong>adjacent</strong> cells that are not walls.</p>
<p>Return <em>the <strong>maximum</strong> number of minutes that you can stay in your initial position before moving while still safely reaching the safehouse</em>. If this is impossible, return <code>-1</code>. If you can <strong>always</strong> reach the safehouse regardless of the minutes stayed, return <code>10<sup>9</sup></code>.</p>
<p>Note that even if the fire spreads to the safehouse immediately after you have reached it, it will be counted as safely reaching the safehouse.</p>
<p>A cell is <strong>adjacent</strong> to another cell if the former is directly north, east, south, or west of the latter (i.e., their sides are touching).</p>
