using System;

using System.Linq;

public class Program

{

    static int count = 0;

    public static void Main()

    {

        var str = "облако".ToCharArray();

        GetCombinations(string.Empty, str);

    }

    private static void GetCombinations(string currentStr, char[] left) {

        for (int i = 0; i < left.Length; i++) {

            var result = currentStr + left[i];

            if (left.Length == 1)

            {

                count++;

                Console.WriteLine(count + ": " + result);

                return;

            }

            var next = left.Take(i).Concat(left.Skip(i+1)).ToArray();

            GetCombinations(result, next);

        }

    }

}