package no086;

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static final int[] di = {0,-1,0,1};
	public static final int[] dj = {1,0,-1,0};
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		char[][] map = new char[n+2][];
		int channels = 0;
		for(int i=1;i<=n;i++) {
			map[i] = ("#" + sc.next() + "#").toCharArray() ;
		}
		map[0] = new char[m+2];
		map[n+1] = new char[m+2];
		Arrays.fill(map[0], '#');
		Arrays.fill(map[n+1], '#');
		for(int i=1;i<=n;i++) {
			for(int j=1;j<=m;j++) {
				if (map[i][j] == '.') {
					channels++;
				}
			}
		}
		for(int si=1;si<=n;si++) {
			for(int sj=1;sj<=m;sj++) {
				if (map[si][sj] == '#') {
					continue;
				}
				for(int sd=0;sd<4;sd++) {
					int i = si;
					int j = sj;
					int dir = sd;
					boolean[][] used = new boolean[n+2][m+2];
					for(int i2=0;i2<=n+1;i2++) {
						for(int j2=0;j2<=m+1;j2++) {
							if (map[i2][j2] == '#') {
								used[i2][j2] = true;
							}
						}
					}
					int count = 0;
					while(true) {
						if (used[i][j]) {
							if (i == si && j == sj && count == channels) {
								System.out.println("YES");
								return;
							}
							break;
						}
						used[i][j] = true;
						count++;
						int ni = i + di[dir];
						int nj = j + dj[dir];
						if (used[ni][nj] && !(ni == si && nj == sj)) {
							int dir2 = (dir+1) % 4;
							if (used[i+di[dir2]][j+dj[dir2]] && !(i+di[dir2] == si && j+dj[dir2] == sj)) {
								break;
							}
							dir = dir2;
						}
						i += di[dir];
						j += dj[dir];
					}
				}
			}
		}
		System.out.println("NO");
	}

}