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

int main() {
    int N, M;
    string A[110];
    cin >> N >> M;
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }

    int total = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            total += (A[i][j] == '.');
        }
    }

    const int dx[] = {1, 0, -1, 0};
    const int dy[] = {0, 1, 0, -1};

    bool ans = false;

    auto ok_x = [&](int x) {
        return x >= 0 && x < N;
    };
    auto ok_y = [&](int y) {
        return y >= 0 && y < M;
    };
    auto ok = [&](int x, int y) {
        return ok_x(x) && ok_y(y) && A[x][y] == '.';
    };

    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            for (int start_dir = 0; start_dir < 4; start_dir++) {
                int x = i, y = j, dir = start_dir;
                int seen[110][110] = {};
                for (int cnt = 1; cnt <= (N + M) * 2; cnt++) {
                    seen[x][y] = 1;
                    if (ok(x + dx[dir], y + dy[dir])) {
                        x += dx[dir];
                        y += dy[dir];
                    } else {
                        (++dir) %= 4;
                        if (ok(x + dx[dir], y + dy[dir])) {
                            x += dx[dir];
                            y += dy[dir];
                        } else {
                            break;
                        }
                    }
                    if (i == x && j == y) {
                        if (cnt == total)
                            ans = true;
                        else
                            break;
                    }
                    if (seen[x][y])
                        break;
                }
            }
        }
    }

    cout << (ans ? "YES" : "NO") << endl;
}