using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var numsNo = new[] {10,1,2,3,4,5};

        var numsYes = new[] {1,2,3,4,5};

        var orderedNo = IsOrdered(numsNo);

        var orderedYes = IsOrdered(numsYes);

        var singleIteratorNo = SingleIteratorIsOrdered(numsNo);

        var singleIteratorYes = SingleIteratorIsOrdered(numsYes);

        Console.WriteLine("Multi Expect false: " + orderedNo);

        Console.WriteLine("Multi Expect true: " + orderedYes);

        Console.WriteLine("Single Expect false: " + singleIteratorNo);

        Console.WriteLine("Single Expect true: " + singleIteratorYes);  

    }

    private static bool IsOrdered(IEnumerable<int> source)

    {

        return !source

            .Zip(source.Skip(1))

            .Any(x => x.First > x.Second);  

    }

    private static bool SingleIteratorIsOrdered(IEnumerable<int> source)

    {

        var last = int.MinValue;

        return !source.Any(x => {

            var result = x < last;

            last = x;

            return result;

        });

    }

}