php 7 count result in database

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("host", "username", "password","db_name");
mysqli_set_charset($link, "utf8mb4");

$result = mysqli_query($link, "SELECT count(*) FROM blackandwhite");
$num_rows = mysqli_fetch_row($result)[0];

echo "$num_rows Rows\n";