using System;

public struct S{
    public static S  operator +(bool? b, S y)
    {
        return new S();
    }
    
    public static S  operator +(S x)
    {
        return new S();
    }
}


public class Test
{
	public static void Main()
	{
		// the trick is to use the fact that the operator +
		// is both unary and binary.
		var o = 1 is bool?  +new S() is int ? null : default(bool?);
		var p = 1 is bool?  +new S() is int ? : default(bool?);
	}
}