#include <bits/stdc++.h>
#include <atcoder/dsu>

int solve(int H, int W, std::vector<std::string> S) {
	atcoder::dsu uf(H + W);
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			if (S[i][j] == '@') {
				uf.merge(i, H + j);
			}
		}
	}
	std::vector<std::vector<int>> g = uf.groups();
	int L = g.size();
	std::vector<int> c(L), d(L);
	for (int i = 0; i < L; i++) {
		for (int u: g[i]) {
			if (u < H) c[i]++;
			else d[i]++;
		}
	}
	std::vector<int> dp1(H + 1, -1), dp2(H + 1, 1e9);
	dp1[0] = 0;
	dp2[0] = 0;
	for (int i = 0; i < L; i++) {
		for (int j = H; j >= 0; j--) {
			if (dp1[j] != -1 && j + c[i] <= H) {
				dp1[j + c[i]] = std::max(dp1[j + c[i]], dp1[j] + d[i]);
				dp2[j + c[i]] = std::min(dp2[j + c[i]], dp2[j] + d[i]);
			}
		}
	}
	int ans = 0;
	for (int i = 0; i <= H; i++) {
		if (dp1[i] != -1) ans = std::max(ans, i * (W - dp1[i]) + (H - i) * dp1[i]);
		if (dp2[i] != 1e9) ans = std::max(ans, i * (W - dp2[i]) + (H - i) * dp2[i]);
	}
	return ans;
}

int naive(int H, int W, std::vector<std::string> S) {
	int ans = 0;
	for (int i = 0; i < (1 << H); i++) {
		for (int j = 0; j < (1 << W); j++) {
			bool ok = true;
			for (int k = 0; k < H; k++) {
				for (int l = 0; l < W; l++) {
					if (S[k][l] == '@' && ((i >> k) & 1) != ((j >> l) & 1)) ok = false;
				}
			}
			if (ok) {
				int c = __builtin_popcount(i), d = __builtin_popcount(j);
				ans = std::max(ans, c * (W - d) + d * (H - c));
			}
		}
	}
	return ans;
}

int main() {
	/*
	int H = 4, W = 4;
	std::random_device rd;
	std::mt19937 en(rd());
	std::vector<std::string> S(H);
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			if (en() % 100 < 50) {
				S[i] += '@';
			} else {
				S[i] += '.';
			}
		}
	}
	int ans1 = solve(H, W, S), ans2 = naive(H, W, S);
	std::cout << ans1 << ' ' << ans2 << '\n';
	if (ans1 != ans2) {
		for (int i = 0; i < H; i++) {
			std::cout << S[i] << '\n';
		}
	}
	*/
	int H, W;
	std::cin >> H >> W;
	std::vector<std::string> S(H);
	for (int i = 0; i < H; i++) {
		std::cin >> S[i];
	}
	std::cout << solve(H, W, S) << '\n';
}