#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};

int tx, ty;
int lx, ly, ldir;

int check(int x, int y, int dir, vector<string>& A) {
	int N = A.size(), M = A[0].length();
	A[y][x] = '#';
	int _dir = (dir + 1) % 4;
	int _x = x + dx[_dir], _y = y + dy[_dir];
	if (_x >= 0 && _x < M && _y >= 0 && _y < N && A[_y][_x] == '.')
		return 1 + check(_x, _y, _dir, A);
	int _x2 = x + dx[dir], _y2 = y + dy[dir];
	if (_x2 >= 0 && _x2 < M && _y2 >= 0 && _y2 < N && A[_y2][_x2] == '.')
		return 1 + check(_x2, _y2, dir, A);
	if (_x == tx && _y == ty) return 1;
	if (_x2 == tx && _y2 == ty) return 1;
	return 0;
}

int main() {
	int N, M; cin >> N >> M;
	vector<string> A(N);
	int cnt = 0;
	for (int i = 0; i < N; i++) {
		cin >> A[i];
		for (int j = 0; j < M; j++)
			if (A[i][j] == '.') cnt++;
	}
	for (int y = 0; y < N; y++)
		for (int x = 0; x < M; x++)
			for (int dir = 0; dir < 4; dir++) {
				if (A[y][x] == '#') continue;
				int _x = x + dx[dir], _y = y + dy[dir];
				if (_x >= 0 && _x < M && _y >= 0 && _y < N && A[_y][_x] == '.') {
					vector<string> _A = A;
					_A[y][x] = '#';
					tx = x; ty = y;
					if (check(_x, _y, dir, _A) == cnt - 1) {
						cout << "YES" << endl;
						return 0;
					}
				}
			}
	cout << "NO" << endl;
}