using System;
using System.IO;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

partial class Solver {
    bool Try(char[,] map) {
        int[] dx = new int[] { 0, -1, 0, 1 };
        int[] dy = new int[] { 1, 0, -1, 0 };
        int buttonCount = map.Cast<char>().Count(c => c == '.');
        int height = map.GetLength(0);
        int width = map.GetLength(1);
        for (int i = 0; i < map.GetLength(0); i++) {
            for (int j = 0; j < map.GetLength(1); j++) {
                if (map[i, j] == '#') continue;
                int step = 0;
                int row = i, col = j;
                var visited = new bool[height, width];
                for (int k = 0; k < 8; k++) {
                    bool moved = false;
                    while (true) {
                        int nRow = row + dy[k % 4];
                        int nCol = col + dx[k % 4];
                        if (0 <= nRow && nRow < height && 0 <= nCol && nCol < width && map[nRow, nCol] == '.' && !visited[nRow, nCol]) {
                            row = nRow;
                            col = nCol;
                            visited[row, col] = true;
                            step++;
                            moved = true;
                        } else {
                            break;
                        }
                    }
                    if (!moved) break;
                }

                if (step == buttonCount && row == i && col == j) {
                    return true;
                }
            }
        }
        return false;
    }

    T[,] Rotate<T>(T[,] array) {
        int height = array.GetLength(0);
        int width = array.GetLength(1);
        var result = new T[width, height];
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                result[j, height - i - 1] = array[i, j];
            }
        }
        return result;
    }

    public void Run() {
        int N = ni();
        int M = ni();
        var A = NextArray(N);

        var map = new char[N, M];
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                map[i, j] = A[i][j];
            }
        }

        bool ans = false;
        for (int i = 0; i < 4; i++) {
            if (Try(map)) {
                ans = true;
                break;
            }
            map = Rotate(map);
        }
        cout.WriteLine(ans ? "YES" : "NO");
    }
}

// PREWRITEN CODE BEGINS FROM HERE
partial class Solver : Scanner {
    public static void Main(string[] args) {
        new Solver(Console.In, Console.Out).Run();
    }

    TextReader cin;
    TextWriter cout;

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        this.cin = reader;
        this.cout = writer;
    }
    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

    public int ni() {
        return NextInt();
    }
    public long nl() {
        return NextLong();
    }
    public string ns() {
        return Next();
    }
}

public class Scanner {
    private TextReader Reader;
    private Queue<String> TokenQueue = new Queue<string>();
    private CultureInfo ci = CultureInfo.InvariantCulture;

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        this.Reader = reader;
    }

    public int NextInt() { return Int32.Parse(Next(), ci); }
    public long NextLong() { return Int64.Parse(Next(), ci); }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        var array = new string[size];
        for (int i = 0; i < size; i++) array[i] = Next();
        return array;
    }
    public int[] NextIntArray(int size) {
        var array = new int[size];
        for (int i = 0; i < size; i++) array[i] = NextInt();
        return array;
    }

    public long[] NextLongArray(int size) {
        var array = new long[size];
        for (int i = 0; i < size; i++) array[i] = NextLong();
        return array;
    }

    public String Next() {
        if (TokenQueue.Count == 0) {
            if (!StockTokens()) throw new InvalidOperationException();
        }
        return TokenQueue.Dequeue();
    }

    public bool HasNext() {
        if (TokenQueue.Count > 0)
            return true;
        return StockTokens();
    }

    private bool StockTokens() {
        while (true) {
            var line = Reader.ReadLine();
            if (line == null) return false;
            var tokens = line.Trim().Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
            if (tokens.Length == 0) continue;
            foreach (var token in tokens)
                TokenQueue.Enqueue(token);
            return true;
        }
    }
}