using System;

using static System.Console;

using System.Collections.Generic;

​

public class Program {

    public static void Main() {

        var list = new List<string>() { "Leão", "Guepardo", "Elefante" };

        var array = new string[3] { "Leão", "Guepardo", "Elefante" };

        WriteLine(list.IndexOf("Elefante"));

        WriteLine(Array.IndexOf(array, "Elefante"));

    }

}