to point to the element after the last one used. If there are not enough elements, throws <code class="computeroutput">std::invalid_argument</code>.</p>
<p><code class="computeroutput">first</code> and <code class="computeroutput">last</code> must be input iterators. </p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="identifier">IntType</span> <a name="id-1_3_34_5_6_22_1_1_1_9_5-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><sp