Reading from XML document

using System.Xml;
using System.Collections.Generic;

public static void Main(string fullpath)
{
    var xmldoc = new XmlDocument();
    xmldoc.Load(fullpath);
    
    var oneValues = new List<string>();
    
    // Getting all XML nodes with the tag name
    var accountNodes = xmldoc.GetElementsByTagName("Account");
    for (var i = 0; i < accountNodes.Count; i++)
    {
        // Use Xpath to find a node
        var account = accountNodes[i].SelectSingleNode("./One");
        if (account != null && account.Attributes != null)
        {
            // Read node attribute
            oneValues.Add(account.Attributes["number"].Value);
        }
    }
}