How to validate two properties which depend on each other?

I have view model with 2 properties: A and B and I want to validate that A < B.

Below is my simplified implementation where I use custom validation rule. Since each property is validated independently, it lead to an anoying issue: if entered A value is invalid, than it stay so even after changing B, since validation of B doesn't know anything about A.

This can be seen on this demo:

A is invalid after entering 11, that's correct since 11 > 2. Changing B to 22 doesn't re-evalute A, I have to edit A to have validation passed.

What I want? I want that after enering 22 into B the red border (validation error) disappears and A = 11, B = 22 would be source values in view model.

How can I in B validation somehow force A validation after new B value is synchronized with source?

View model:

public class ViewModel : INotifyPropertyChanged
{
    int _a;
    public int A
    {
        get => _a;
        set
        {
            _a = value;
            OnPropertyChanged();
        }
    }

    int _b;
    public int B
    {
        get => _b;
        set
        {
            _b = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public virtual void OnPropertyChanged([CallerMemberName] string property = "") =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
}

View:

<StackPanel>
    <TextBox Margin="10" Text="{local:MyBinding A}" />
    <TextBox Margin="10" Text="{local:MyBinding B}" />
</StackPanel>

View code:

public MainWindow()
{
    InitializeComponent();
    DataContext = new ViewModel { A = 1, B = 2 };
}

Binding:

public class MyBinding : Binding
{
    public MyBinding(string path) : base(path)
    {
        UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
        ValidationRules.Add(new MyValidationRule());
    }
}

Validation rule:

public class MyValidationRule : ValidationRule
{
    public MyValidationRule() : base(ValidationStep.ConvertedProposedValue, false) { }

    public override ValidationResult Validate(object value, CultureInfo cultureInfo) => ValidationResult.ValidResult; // not used

    public override ValidationResult Validate(object value, CultureInfo cultureInfo, BindingExpressionBase owner)
    {
        var binding = owner as BindingExpression;
        var vm = binding?.DataItem as ViewModel;
        switch (binding.ResolvedSourcePropertyName)
        {
            case nameof(vm.A):
                if ((int)value >= vm.B)
                    return new ValidationResult(false, "A should be smaller than B");
                break;
            case nameof(vm.B):
                if ((int)value <= vm.A)
                    return new ValidationResult(false, "B should be bigger than A");
                break;
        }
        return base.Validate(value, cultureInfo, owner);
    }
}