Problem:
Score : 300 points

Problem Statement

There is a grid with H rows and W columns, where each square is painted black or white.

You are given H strings S_1, S_2, ..., S_H, each of length W.
If the square at the i-th row from the top and the j-th column from the left is painted black, the j-th character in the string S_i is #; if that square is painted white, the j-th character in the string S_i is ..

Find the number of pairs of a black square c_1 and a white square c_2 that satisfy the following condition:

There is a path from the square c_1 to the square c_2 where we repeatedly move to a vertically or horizontally adjacent square through an alternating sequence of black and white squares: black, white, black, white...

Constraints

1 \leq H, W \leq 400

|S_i| = W (1 \leq i \leq H)

For each i (1 \leq i \leq H), the string S_i consists of characters # and ..

Input

Input is given from Standard Input in the following format:

H W
S_1
S_2
:
S_H

Output

Print the answer.

Sample Input 1

3 3
.#.
..#
#..

Sample Output 1

10

Some of the pairs satisfying the condition are ((1, 2), (3, 3)) and ((3, 1), (3, 2)), where (i, j) denotes the square at the i-th row from the top and the j-th column from the left.

Sample Input 2

2 4
....
....

Sample Output 2

0

Sample Input 3

4 3
###
###
...
###

Sample Output 3

6

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AISing
{
    public class Cell
    {
        public int X, Y;
        public char color;
        public int groupB;

        public List<Cell> GetNextCells(Cell[,] S)
        {
            List<Cell> cells = new List<Cell>();
            Cell cu = S[X, Y - 1];
            Cell cd = S[X, Y + 1];
            Cell cl = S[X - 1, Y];
            Cell cr = S[X + 1, Y];
            Cell[] ccand = { cu, cd, cl, cr };

            foreach (Cell c in ccand)
            {
                if (color == '#')
                {
                    if (c.color == '.' && c.groupB < groupB)
                    {
                        cells.Add(c);
                        c.groupB = groupB;
                    }
                }
                else
                {
                    if (c.color == '#' && c.groupB == 0)
                    {
                        cells.Add(c);
                        c.groupB = groupB;
                    }
                }
            }
            return cells;
        }

    }

    class C
    {

        static void Main(string[] args)
        {
            string[] s1 = Console.ReadLine().Split(' ');
            int H = int.Parse(s1[0]), W = int.Parse(s1[1]);

            Cell[,] S = new Cell[H + 2, W + 2];
            for (int i = 0; i < H + 2; i++)
            {
                for (int j = 0; j < W + 2; j++)
                {
                    S[i, j] = new Cell();
                    S[i, j].X = i;
                    S[i, j].Y = j;
                }
            }

            for (int i = 1; i <= H; i++)
            {
                string ss = Console.ReadLine();
                for (int j = 1; j <= W; j++)
                {
                    Cell c = S[i, j];
                    c.color = ss[j - 1];
                }
            }

            int group = 1;
            long counter = 0;


            for (int i = 1; i <= H; i++)
            {
                for (int j = 1; j <= W; j++)
                {
                    if (S[i, j].color == '#' && S[i, j].groupB == 0)
                    {
                        List<Cell> whiteCells = new List<Cell>();
                        List<Cell> blackCells = new List<Cell>();

                        Cell cellS = S[i, j];
                        List<Cell> searchCells = new List<Cell>();
                        searchCells.Add(cellS);
                        blackCells.Add(cellS);
                        cellS.groupB = group;
                        while (searchCells.Count > 0)
                        {
                            List<Cell> nextCells = new List<Cell>();
                            foreach (Cell cell in searchCells)
                            {
                                var c = cell.GetNextCells(S);
                                nextCells.AddRange(c);
                                if (cell.color == '#') whiteCells.AddRange(c);
                                else blackCells.AddRange(c);
                            }
                            searchCells = nextCells;
                        }
                        counter += (long)whiteCells.Count * blackCells.Count;
                        group++;
                    }
                }
            }
            Console.WriteLine(counter);
        }

    }
}