mlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s1</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s2</span><span class="special">;</span>

<span class="comment">// Set the logical operation timer to 15 seconds.</span>
<span class="identifier">stream</span><span class="special">.</span><span class="i