echo'<form name="form" action="" method="POST">
        Birinchi sonni kiriting:<br>
        <input type="number" name="son1" required><br>
        Ikkinchi sonni kiriting:<br>
        <input type="number" name="son2" required><br>
        <input name="yech" type="submit" value="Yechimni ko\'rish">
    </form>';