Test.cs

using System;
using System.IO;

class Value
{
    private readonly int x;

    public Value(int x)
    {
        this.x = x;
    }

    public static implicit operator int(Value value) => value.x;
}

class Test
{
    static void Main()
    {
        int a = 10;
        Value b = new Value(20);
        Console.WriteLine(a + b);
    }
}