using System;
using System.Linq;

public class Test
{
	public static void Main()
	{
		string[] arrayEnglishMonth = { "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER" };
        
        var index = arrayEnglishMonth.Select((v, i) => new { v, i })
                                     .Where(i => i.v.StartsWith("AUG"))
                                     .Select(i => i.i)
                                     .First();
        Console.WriteLine(index);
	}
}