Untitled

using System;
using System.Collections.Generic;

class A {
    public int a;
    
    public A(int value) {
        this.a = value;
    }
    
    public override bool Equals(object other) {
        A other_a = (A)other;
        
        return this.a == other_a.a;
    }
    
    public override int GetHashCode() {
        return this.a;
    }
    
    public override String ToString() {
        return "a:" + this.a;
    }
}

public class Program
{
	public static void Main()
	{
        A a = new A(1);
        A b = new A(2);
        
        Dictionary< A , int > d = new Dictionary< A , int >();
        
        d.Add(a, 1);
        d.Add(b, 2);
        
        Console.WriteLine(a);
        Console.WriteLine(b);
        Console.WriteLine($"eq {a.Equals(b)}");
        Console.WriteLine($"hash {a.GetHashCode() == b.GetHashCode()}");
        
        foreach (KeyValuePair<A, int> kv in d)
		{
			 Console.WriteLine($"key：{kv.Key}, value：{kv.Value}");
		}
        
		a.a = 2;
		
        Console.WriteLine(a);
        Console.WriteLine(b);
        Console.WriteLine($"eq {a.Equals(b)}");
        Console.WriteLine($"hash {a.GetHashCode() == b.GetHashCode()}");
        
        foreach (KeyValuePair<A, int> kv in d)
		{
			 Console.WriteLine($"key：{kv.Key}, value：{kv.Value}");
		}
        
        Dictionary< A , int > new_d = new Dictionary< A , int >();
        
        new_d.Add(a, 1);
        new_d.Add(b, 2);
        
        foreach (KeyValuePair<A, int> kv in new_d)
		{
			 Console.WriteLine($"key：{kv.Key}, value：{kv.Value}");
		}
	}
}