using System;

using System.Collections.Generic;

using System.Linq;

​

class MainClass {

    private class Person

    {

        public int Id { get; init; }

​

        public string Name { get; init; }

    }

​

    public static void Main(string[] args)

    {

        var people = new List <Person>()

        {

            new Person() { Id = 1, Name = "Alex" },

            new Person() { Id = 2, Name = "Franco" },

            new Person() { Id = 3, Name = "Gabriel" },

            new Person() { Id = 4, Name = "José" },

        };

​

        var peopleById = people.ToDictionary(

            p => p.Id,

            p => p);

​

        System.Console.WriteLine(peopleById[4].Name);

    }

}