PGM viewer - Tutorial C# Sharp

using System;
using System.IO;
public class readerImagePGM
{
    public static void Main()
    {
        // Read name file PGM
        Console.WriteLine("Enter name of file PGM");
        string name = Console.ReadLine();

        // Read all data
        FileStream filePGM = File.OpenRead(name);
        byte[] data = new byte[filePGM.Length];
        filePGM.Read(data, 0, filePGM.Length);
        filePGM.Close();

        // Read mesures file PGM
        string mesures = "";
        int i = 3;
        do
        {
            mesures += Convert.ToChar(data[i]);
            i++;
        }
        while (data[i] != 10);
        i++;

        string[] size;
        int width, height;

        size = mesures.Split(' ');
        width = Convert.ToInt32(size[0]);
        height = Convert.ToInt32(size[1]);

        // Read color tone PGM
        string colorTone = "";
        do
        {
            colorTone += Convert.ToChar(data[i]);
            i++;
        }
        while (data[i] != 10);
        i++;

        // Read pixels of PGM
        int amount = 0;
        for (int j = i; j < filePGM.Length; j++)
        {
            if (data[j] >= 200)
                Console.Write(" ");
            else if (data[j] >= 150 || data[j] <= 199)
                Console.Write(".");
            else if (data[j] >= 100 || data[j] <= 149)
                Console.Write("-");
            else if (data[j] >= 50 || data[j] <= 99)
                Console.Write("=");
            else if (data[j] >= 0 || data[j] <= 49)
                Console.Write("#");

            amount++;

            if (amount % width == 0)
                Console.WriteLine();
        }
    }
}