How can I get Xpath Count in Selenium WebDriver?

This is my HTML page

```
<tbody xmlns="http://www.w3.org/1999/xhtml">
<tr class="odd">
    <td>1</td>
    <td>Cash</td>
    <td>
        <input type="checkbox" id="p1" checked="checked" value="1" name="productAccess"/>
        <input type="hidden" value="1" name="__checkbox_productAccess"/>
    </td>
</tr>
<tr class="even">
    <td>2</td>
    <td>Saving</td>
    <td>
        <input type="checkbox" id="p2" checked="checked" value="2" name="productAccess"/>
        <input type="hidden" value="2" name="__checkbox_productAccess"/>
    </td>
</tr>

```

I used 

```
int product_count = driver.findElements(By.xpath("//id('product')/x:tbody/x:tr[1]")).size();

```

But always I am getting wrong xpath, anybody can help me?