using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    static void Main()

    {

        var arr = new[]

        {

            new[]{3,1},

            new[]{2,5,7},

            new[]{1,5,8,3,1,4},

            new[]{6,8,7,1},

            new[]{4},

            new[]{6},

            new[]{6,2,5}

        };

        FindAndPrintDiagonals(arr);

    }

​

    static void FindAndPrintDiagonals(int[][] input)

    {

        var diagonalsFromLeft = FindDiagonalsWhichStartsFromLeft(input);

        var diagonalsFromTop = FindDiagonalsWhichStartsFromTop(input);

        foreach (var diagonal in diagonalsFromLeft.Union(diagonalsFromTop))

        {

            Console.WriteLine(string.Join(" ", diagonal));

        }

    }

​

    static List<List<int>> FindDiagonalsWhichStartsFromLeft(int[][] input)

    {

        var diagonals = new List<List<int>>();

        for (int row = input.Length - 1; row > 0; row--)

        {

            int rowIndex = row, columnIndex = 0;

            var diagonal = new List<int>()

            {

                input[rowIndex][columnIndex]

            };

​

            GetDiagonal(input, diagonal, rowIndex, columnIndex);

            if (diagonal.Count > 1)

                diagonals.Add(diagonal);

        }

        return diagonals;

    }

​

    static List<List<int>> FindDiagonalsWhichStartsFromTop(int[][] input)

    {

        var diagonals = new List<List<int>>();

        for (int column = 0; column < input[0].Length; column++)

        {

            int rowIndex = 0, columnIndex = column;

            var diagonal = new List<int>()

            {

                input[rowIndex][columnIndex]

            };

​

            GetDiagonal(input, diagonal, rowIndex, columnIndex);

            if (diagonal.Count > 1)

                diagonals.Add(diagonal);

        }

        return diagonals;

    }

​

    static void GetDiagonal(int[][] input, List<int> diagonal, int rowIndex, int columnIndex)

    {

        while (true)

        {

            rowIndex++; columnIndex++;

            if (rowIndex >= input.Length || columnIndex >= input[rowIndex].Length)

                break;

​

            diagonal.Add(input[rowIndex][columnIndex]);

        }

    }

}