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 Scala (2.11.7) (judge verdict: Runtime Error)

import scala.io.StdIn

object Main extends App {
  val Array(h, w) = StdIn.readLine.split(" ").map(_.toInt)
  val table = Iterator.continually(StdIn.readLine)
    .take(h)
    .map(_.map(ch => if(ch == '#') true else false).toArray)
    .toArray

  val ans = {
    val dx = Array(0, 1, 0, -1)
    val dy = Array(-1, 0, 1, 0)
    var res = 0;

    def f(y:Int, x:Int):Int = {
      val visit = Array.ofDim[Boolean](h,w)

      def dfs(ey:Int, ex:Int):Unit = {
        if(table(ey)(ex) != table(y)(x) || visit(ey)(ex)) return
        else {
          visit(ey)(ex) = true 
          (0 until 4).foreach(i => {
            val y = ey + dy(i)
            val x = ex + dx(i)
            if(0 <= y && y < h && 0 <= x && x < w) {
              dfs(y, x)
            }
          })
        }
      }

      dfs(y, x)

      val a = for {
        i <- 0 until h
        j <- 0 until w
        if !table(i)(j)
      } { if(visit(i)(j)) res += 1 }
      res
    }

    val ret = for {
      i <- 0 until h
      j <- 0 until w
      if table(i)(j)
    } yield f(i,j)

    ret.sum
  }

  println(ans)
}