for with if & ifelse

I have 5 images named 1.png, 2.png, 3.png, 4c.png, & 5.png.

I want to show this images in PHP like this but it shows like this.

My code is:-

<div class="row">
<?php 
$images = "/downloads/vf/images/";
for ($i = 1; $i <= 5; $i++):
    if (!file_exists($_SERVER['DOCUMENT_ROOT'].$images.$i.".png"))

        continue; // Skip this iteration if it can't find the file 
    ?>
    <div class="col-md-2">
      <div class="thumbnail">
        <a href="<?php echo $details . $i;?>.php">
          <img src="<?php echo $images;?><?php echo $i;?>.png" alt="<?php echo $i;?>">
        </a>
      </div>
    </div>
<?php endfor; ?>

<?php 
$images = "/downloads/vf/images/";
for ($i = 1; $i <= 5; $i++):
    if (!file_exists($_SERVER['DOCUMENT_ROOT'].$images.$i."c.png"))

        continue; // Skip this iteration if it can't find the file 
    ?>
    <div class="col-md-2">
      <div class="thumbnail">
        <a href="<?php echo $details . $i;?>.php">
          <img src="<?php echo $images;?><?php echo $i;?>c.png" alt="<?php echo $i;?>">
        </a>
      </div>
    </div>
<?php endfor; ?>

</div>

Can it be changed in if, elseif.

I want but it is.