public static void Main()
string longString = "J44I9079PM37";
Console.WriteLine(longString[3] + "\n");
string si = String.Empty;
Console.WriteLine("Choose a method:");
Console.WriteLine("String Builder:\tsb\nString Increment:\tsi");
string reply = Console.ReadLine();
for (int i = 0; i < longString.Length; i++)
if (!Char.IsNumber(longString[i]))
StringBuilder sb = new StringBuilder(longString);
for (int i = 0; i < sb.Length; i++)
if (Char.IsNumber(sb[i]))
Console.WriteLine("Unrecognized response.");
while (isLooping == true);