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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Convert;
using static System.Math;

class Program
{
    private static P[,] p;
    struct bw
    {
        public int w;
        public int b;
    }
    struct P
    {
        public int h;
        public int w;
        public bool isBlack;
        public bool isSearch;
        public P(int h,int w,bool isBlack)
        {
            this.h = h;
            this.w = w;
            this.isBlack = isBlack;
            isSearch = false;
        }
    }
    static void Main(string[] args)
    {
        var hw = Array.ConvertAll(ReadLine().Split(' '), int.Parse);
        var s = new string[hw[0]];
        for (var i = 0; i < hw[0]; i++)
            s[i] = ReadLine();
        p = new P[hw[0], hw[1]];
        var res = 0;
        for(var i = 0; i < hw[0]; i++)
        {
            for(var j = 0; j < hw[1]; j++)
            {
                p[i, j] = new P(i, j, s[i][j] == '#');
            }
        }
        for(var i = 0; i < hw[0]; i++)
        {
            for(var j = 0; j < hw[1]; j++)
            {
                if (!p[i, j].isSearch)
                {
                    var bw = new bw();
                    Get(i, j, hw[0], hw[1],ref bw);
                    res += bw.b * bw.w;
                }
            }
        }
        WriteLine(res);
    }

    private static void Get(int i,int j,int h,int w,ref bw bw)
    {
        p[i, j].isSearch = true;
        if (p[i, j].isBlack) bw.b++;
        else bw.w++;
        if (i != 0 && !p[i-1,j].isSearch && (p[i - 1, j].isBlack ^ p[i,j].isBlack))
        {
            Get( i - 1, j, h, w,ref bw);
        }
        if (j != 0 && !p[i,j-1].isSearch&& (p[i, j - 1].isBlack ^ p[i,j].isBlack))
        {
            Get(i, j - 1,h,w,ref bw);
        }
        if (i != h - 1 && !p[i+1,j].isSearch && (p[i + 1, j].isBlack ^ p[i,j].isBlack))
        {
            Get( i + 1, j,h,w,ref bw);
        }
        if (j != w - 1 && !p[i,j+1].isSearch && (p[i, j + 1].isBlack ^ p[i,j].isBlack))
        {
            Get( i, j + 1,h,w,ref bw);
        }
    }
    private const string ALFA = "abcdefghijklmnopqrstuvwxyz";
    private const int MOD = 1000000007;
}