#include <iostream>
#include <vector>
#define repeat(i,n) for (int i = 0; (i) < int(n); ++(i))
using namespace std;
bool solve(int h, int w, vector<string> const & f) {
    auto is_on_field = [&](int y, int x) { return 0 <= y and y < h and 0 <= x and x < w; };
    auto pred = [&](int y, int x) { return is_on_field(y, x) and f[y][x] == '.'; };
    const int dy[] = { 0, -1, 0, 1 }; // counter-clockwise
    const int dx[] = { 1, 0, -1, 0 };
    const int table[] = { 0, 1, 2, 1, 2, 3 };
    int total = 0; repeat (y,h) repeat (x,w) total += pred(y, x);
    repeat (y0,h) repeat (x0,w) if (pred(y0, x0)) {
        repeat (d0,4) {
            int y = y0;
            int x = x0;
            int cnt = 0;
            for (int phase = 0; phase < 6; ) {
                if (cnt and y == y0 and x == x0) break;
                ++ cnt;
                int ny = y + dy[(d0 + table[phase]    ) % 4];
                int nx = x + dx[(d0 + table[phase]    ) % 4];
                int ry = y + dy[(d0 + table[phase] + 3) % 4];
                int rx = x + dx[(d0 + table[phase] + 3) % 4];
                if (phase == 2 and pred(ry, rx)) {
                    y = ry;
                    x = rx;
                    ++ phase;
                } else if (pred(ny, nx)) {
                    y = ny;
                    x = nx;
                } else {
                    -- cnt;
                    ++ phase;
                }
            }
            if (y == y0 and x == x0 and cnt == total) return true;
        }
    }
    return false;
}
int main() {
    int h, w; cin >> h >> w;
    vector<string> f(h); repeat (y,h) cin >> f[y];
    cout << (solve(h, w, f) ? "YES" : "NO") << endl;
    return 0;
}