using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
public class Test
{
public static void Main()
{
List<string> _ids = new List<string>() { "aaa", "bbb", "ccc", "ddd" };
var first = _ids.First();
var last = _ids.Last();
Console.WriteLine(first);
Console.WriteLine(last);
}
}
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