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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <vector>
#include <string>

using namespace std;
int H, W;
vector<vector<bool>>ban;
vector<vector<bool>>visited;
vector<int> dfs(int h, int w, bool iswhite) {
	visited[h][w] = true;
	vector<int>ret(2); ret[iswhite]++;
	int move[4][2] = { {1,0},{-1,0} , { 0,1 }, { 0,-1 } };
	for (int i = 0; i < 4; i++) {
		int x = h + move[i][0]; int y = w + move[i][1];
		if (0 <= x && x < H && 0 <= y && y < W&&ban[h][w] != ban[x][y] && !visited[x][y]) {
			auto v = dfs(x, y, !iswhite);
			ret[0] += v[0]; ret[1] += v[1];
		}
	}
	return ret;
}
int main() {
	cin >> H >> W;
	ban = vector<vector<bool>>(H, vector<bool>(W));
	visited = vector<vector<bool>>(H, vector<bool>(W));
	for (int i = 0; i < H; i++) {
		string s; cin >> s;
		for (int j = 0; j < W; j++)ban[i][j] = s[j] == '.';
	}
	int ret = 0;
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			if (!ban[i][j] && !visited[i][j]) {
				auto x = dfs(i, j, false);
				ret += x[0] * x[1];
			}
		}
	}
	cout << ret << endl;
	return 0;
}