ExtensionMethods.cs

namespace ExtensionMethods
{

    public static class MyExtension
	{
			public static List<string> ParseName(string s)
			{
				string[] lst = s.Split(new char[]{'.', ',', ' ', '(', ')', '-', '+', '^', '*', '/'}, StringSplitOptions.RemoveEmptyEntries);
				List <string> ans = new List<string>();
				foreach(var str in lst)
				{
					if(str[0]>='A' && str[0]<='Z' && str[str.Length-1]>='0' && str[str.Length-1]<='9')
					{
						ans.Add(str);
					}
				}
				return ans;
			}

			public static Tuple<int, int> NameToCoordinates(string s)
			{
				int i=0, x=0, y=0;
				while(s[i]>='A' && s[i]<='Z')
				{
					x=x*26+Convert.ToInt32(s[i]-65+1);
					i++;
				}
				int j = i;
				while(i<s.Length && s[i]>='0' && s[i]<='9')
				{
					y = y*10+Convert.ToInt32(s[i]-48);
					i++;
				}
				return new Tuple<int, int>(x, y);
			}
			public static int Convert26To10(string s)
			{
				int i=0, x=0;
				while(i<s.Length && s[i]>='A' && s[i]<='Z')
				{
					x=x*26+Convert.ToInt32(s[i]-65+1);
					i++;
				}
				if(i!=s.Length)
				{
					throw new ArgumentException("Invalid argument");
				}
				return x;
			}
			
	}
}