<?php
$n = trim(fgets(STDIN));
$number = explode(" ", trim(fgets(STDIN)));
$num = array_unique($number);
sort($num);
// print_r($num);
$i = array();
foreach ($num as $key => $value){
    $i[] = $num[$key] - $num[$key - 1];
}
sort($i);
echo $i[1];