using System;
	using System.Collections.Generic;
	
	public class Program
	{
	    public static void Main(string[] args)
	    {
	        int[] arr = { 0, 1, 2, 3, 4, 3, 2, 1, 0, 1, 2 };
	        
	        Console.WriteLine("arr");
	        foreach (var intervalo in arr.IntervalosCrescimento())
	        {
	            Console.WriteLine($"Start {intervalo.Item1}, end {intervalo.Item2}, sinal {intervalo.Item3}");
	        }
	        
	        int[] arr2 = { 0, 1, 2, 3, 3, 3, 4, 5, 6, -1, -8, 0, 8 };
	
	        Console.WriteLine();
	        Console.WriteLine("arr2");
	        foreach (var intervalo in arr2.IntervalosCrescimento())
	        {
	            Console.WriteLine($"Start {intervalo.Item1}, end {intervalo.Item2}, sinal {intervalo.Item3}");
	        }
	    }
	}
	
	public static class ExtensionMethod
	{
	    public static IEnumerable<Tuple<int, int, int>> IntervalosCrescimento<T>(this IEnumerable<T> en) where T : IComparable
	    {
	        bool first = true;
	
	        Tuple<int, int, int> result;
	
	        int start = -1;
	        int end = -1;
	
	        T previous = default(T);
	        
	        int? previousSign = null;
	        int? sign = null;
	
	        int index = 0;
	
	        foreach (T current in en)
	        {
	            if (first)
	            {
	                first = false;
	                start = index;
	                previous = current;
	            }
	            else
	            {
	                sign = current.CompareTo(previous);
	
	                if (previousSign == null)
	                {
	                    previousSign = sign;
	                }
	                else if (previousSign != sign)
	                {
	                    end = index;
	
	                    result = Tuple.Create(start, end, previousSign.Value);
	
	                    start = index;
	                    previousSign = sign;
	
	                    yield return result;
	                }
	               
	        	    previous = current;
    	        	++index;
	            }
	         }
	
	        end = index;
	 
	        if (start < end)
	            yield return Tuple.Create(start, end, sign.Value);
	    }
	}