Dict - ref- bool isNumber = value.All(char.IsDigit);

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//You have been tasked to create a referenced dictionary, or in other words a dictionary, which knows how to reference itself.
//You will be given several input lines, in one of the following formats:
//•   {name} = {value}
//•   {name} = {secondName}
//The names will always be strings, and the values will always be integers.
//In case you are given a name and a value, you must store the given name and its value. If the name already EXISTS, you must CHANGE //its value with the given one.
//In case you are given a name and a second name, you must store the given name with the same value as the value of the second name. If //the given second name DOES NOT exist, you must IGNORE that input.
//When you receive the command “end”, you must print all entries with their value, by order of input, in the following format:
//{entry} === {value}

namespace dict_ref
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine();
            Dictionary<string, int> dictionary = new Dictionary<string, int>();

            while (input != "end")
            {
                string[] inputData = input.Split(' ').ToArray();
                string name = inputData[0];
                string value = inputData[inputData.Length - 1];

                bool isNumber = value.All(char.IsDigit);
                if (isNumber)
                {
                    dictionary[name] = int.Parse(value);
                }
                else
                {
                    if (dictionary.ContainsKey(value))
                    {
                        var temp = dictionary[value];
                        dictionary[name] = temp;
                    }
                }

                input = Console.ReadLine();
            }
            foreach (var entry in dictionary)
            {
                Console.WriteLine($"{entry.Key} === {entry.Value}");
            }
        }
    }
}