using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
        var re = new Regex(@"\b[аеоиуюэяёы][а-яё][аеоиуюэяёы]\b",
                           RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
		string text = Console.In.ReadToEnd();
        foreach (Match match in re.Matches(text))
            Console.WriteLine($"  --> match at index {match.Index}, length {match.Length}, text {match.Value}");
	}
}

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

0LDQs9CwCtC+0LPQvgrQvdC10YIK0YLRgNC4CtGH0LXRgtGL0YDQtQpxd2UK0LDQs9CwINC+0LPQviDRg9Cz0YMg0YXRgNGOINCz0LDQsiDQvNGP0YMg0YLQv9GA0YMg0L3QviDRi9GL0Ys=

ага
ого
нет
три
четыре
qwe
ага ого угу хрю гав мяу тпру но ыыы