#include <bits/stdc++.h>
using namespace std;
#include <atcoder/dsu>
using namespace atcoder;

int main() {
    int H, W; cin >> H >> W;
    dsu d(H+W);
    vector<string> S(H);
    for (int i = 0; i < H; i++) {
        cin >> S[i];
        for (int j = 0; j < W; j++) {
            if (S[i][j] == '@') {
                d.merge(i, j+H);
            }
        }
    }    
    vector<vector<int>> G = d.groups();
    int K = (int)G.size();
    vector dp(K+1, vector(H+1, vector<bool>(W+1, false)));
    dp[0][0][0] = true;
    for (int i = 0; i < K; i++) {
        vector<int> g = G[i];
        int rcnt = 0, ccnt = 0;
        for (int v : g) {
            if (v < H) rcnt++;
            else ccnt++;
        }
        for (int j = 0; j <= H; j++) {
            for (int k = 0; k <= W; k++) {
                if (dp[i][j][k]) {
                    //黒く塗る
                    dp[i+1][j+rcnt][k+ccnt] = true;
                    //黒く塗らない
                    dp[i+1][j][k] = true;
                }
            }
        }
    }
    int ans = 0;
    for (int i = 0; i <= H; i++) {
        for (int j = 0; j <= W; j++) {
            if (dp[K][i][j]) {
                ans = max(ans, i*(W-j)+(H-i)*j);
            }
        }
    }
    cout << ans << endl;
}