#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (ll i = (s); i < (ll)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (ll i = (ll)(s - 1); i >= (ll)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") {
    cout << (f ? yes : no) << "\n";
}

void solve() {
    int h, w;
    cin >> h >> w;
    vector<string> s(h);
    rep(i, h) cin >> s[i];
    int tot = 0;
    rep(i, h) rep(j, w) if (s[i][j] == '.')++ tot;
    int dx[] = {0, -1, 0, 1};
    int dy[] = {-1, 0, 1, 0};
    auto isOutOfRange = [](int h, int w, int H, int W) {
        return h < 0 || h >= H || w < 0 || w >= W;
    };
    auto jd = [&](int sy, int sx, int d) {
        int cnt = 0;
        int right = 0;
        int x = sx, y = sy;
        vector<vi> used(h, vi(w));
        while (1) {
            int nx = x + dx[d], ny = y + dy[d];
            int nd = d;

            if (isOutOfRange(ny, nx, h, w) || s[ny][nx] == '#' || used[ny][nx]) {
                nd = (d + 1) % 4;
                nx = x + dx[nd], ny = y + dy[nd];
                if (isOutOfRange(ny, nx, h, w) || s[ny][nx] == '#' || used[ny][nx]) {
                    nd = (d + 3) % 4;
                    nx = x + dx[nd], ny = y + dy[nd];
                    if (isOutOfRange(ny, nx, h, w) || s[ny][nx] == '#') {
                        return false;
                    }
                    ++right;
                }
            }
            cnt++;
            y = ny;
            x = nx;
            d = nd;
            used[y][x] = 1;
            if (sy == y && x == sx) {
                return cnt == tot && right <= 1;
            }
        }
        return false;
    };
    rep(i, h) rep(j, w) {
        if (s[i][j] == '.') {
            rep(k, 4) {
                if (jd(i, j, k)) {
                    cout << "YES" << '\n';
                    return;
                }
            }
        }
        cout << "NO" << '\n';
        return;
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}