some codility challenge

sutdents.php

<?php
function solution($A) {
    // write your code in PHP7.0
    $a = 0;
     $c = count($A);
     for( $i = 0; $i <= $c; $i++  ){
         if( $A[$i] <= ( current($A) + 1 ) ){
             $a++;
         }
     }


     //need to satify the test by output of 3;
     return $a;
}

$A = [1, 3, 2, 2, 2, 2, 3,  6, 5, 5, 5, 8, 9, 10];
echo "<pre>";
print_r(solution($A));