using System;

class Graph

{

    int[,] matrix;

    string[] labels;

    public Graph(int size)

    {

        matrix = new int[size, size];

        labels = new string[size];

        int index = 0;

        for(char letter = 'A'; letter < 'Z' && index < size; letter++, index++)

        {

            labels[index] = letter.ToString();

        }

    }

    public void AddEdge(string from, string to)

    {

        // get index of source vertex using from

        // get index of dest vertex using to

        int sourceIndex = 3;

        int destIndex = 4;

        matrix[sourceIndex, destIndex] = 1;

    }

    public void ShowTheMess()

    {

        // loop, and loop to go through the array

    }

    public int GetLabelIndex(string lable)

    {

        return Array.IndexOf(labels, lable);

    }

}

​

public class Program

{

    public static void Main()

    {

        Graph g = new Graph(5);

        Console.WriteLine(g.GetLabelIndex("A"));

        Console.WriteLine(g.GetLabelIndex("C"));

        Console.WriteLine(g.GetLabelIndex("E"));

    }

}