<?php
    $input = stream_get_contents($_fp);
    $lines = preg_split('/\R/', $input, -1, PREG_SPLIT_NO_EMPTY);
    array_shift($lines);
    $ipv4_pattern = '/^(([01]?[0-9]{0,2}|2[0-5]?[0-5]?)\.){3}([01]?[0-9]{0,2}|2[0-5]?[0-5]?)$/';
    $ipv6_pattern = '/^(([a-fA-F0-9]{1,4}):){7}[a-fA-F0-9]{1,4}$/';
    foreach($lines as $line) {
        $result = 'Neither';
        if (preg_match($ipv4_pattern, $line)) {
            $result = 'IPv4';
        } elseif (preg_match($ipv6_pattern, $line)) {
            $result = 'IPv6';
        }
        
        echo $result . PHP_EOL;
    }