how to declare multiple session variables according to the length of array(php)

enter code here
session_start();
$imgList = $_REQUEST['imgList'];//comes through post (jquery)
$i=0;
$a=explode(',',$imgList); 
$abc=count($a);
for ($e=0;$e<$abc;$e++)
{
echo $_SESSION['c+$i']=$a[$e];
$i++;
}
echo $_SESSION['c+$i'];//this returns the last value
echo count($_SESSION['c+$i']);//returns only length 1
echo count($i);// returns only length 1

i dont know why more than one variable are not initilizing. can anyone please tell me about htis problem or fix this.i"ll be very thankful to you for this favor