function clear_value(obj){
    label = document.getElementById('lb_for_'+obj.id);
    if (obj.value == label.value)
        obj.value = '';
}
function fill_value(obj){
    label = document.getElementById('lb_for_'+obj.id);
    if (obj.value == '')
        obj.value = label.value;
}
function check_form(){
    i=1;
    while (i<=3)
    {
        field = document.getElementById(i);
        lb_field = document.getElementById('lb_for_'+i);
        if (field.value == lb_field.value)
        {
            alert('Все поля обязательны для заполнения!');
            return false;
        }
        i+=1;
    }
    return true;
}