<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $field1 = $_POST['field1'] ?? null;
    $field2 = $_POST['field2'] ?? null;

    if ($field1 && $field2) {
        if (strlen($field1) == (int) $field2) {
            header('Location: nav_post_test_post_redirected_good.html', true, 302);
            exit;
        }
    }
}

header('Location: nav_post_test_post_redirected_fail.html', true, 302);
exit;