using System; using System.Diagnostics; using System.Collections.Generic; using System.Linq; using Enu = System.Linq.Enumerable; class Solution { int H, W; int[,] board; List plist; void calc() { rio(out H, out W); board = new int[H, W]; plist = new List(); for (int i = 0; i < H; i++) { var s = Console.ReadLine(); for (int j = 0; j < W; j++) { if (s[j] == '#') { board[i, j] = 1; plist.Add(new point(j, i)); } else board[i, j] = 0; } } if (plist.Count % 2 == 1 || plist.Count == 0) { Console.WriteLine("NO"); return; } bool ans = false; for (int dy = -H + 1; dy < H; dy++) { for (int dx = -W + 1; dx < W; dx++) { if (dx == 0 && dy == 0) continue; int[,] b = new int[H, W]; Array.Copy(board, b, H * W); for (int y = 0; y < H; y++) { for (int x = 0; x < W; x++) { if (b[y, x] == 0) continue; if (check(x, y, dx, dy)) { b[y, x] = 0; b[y + dy, x + dx] = 0; } } } ans = ans || b.ToJagArray().All(a => a.All(e => e == 0)); } } Console.WriteLine(ans ? "YES" : "NO"); } bool check(int x, int y, int dx, int dy) { int xx = x + dx, yy = y + dy; return 0 <= xx && xx < W && 0 <= yy && yy < H && board[yy, xx] == 1; } static void Main(string[] args) { new Solution().calc(); } #region static int ri() { return int.Parse(Console.ReadLine()); } static int[] ria(int n) { if (n <= 0) { Console.ReadLine(); return new int[0]; } else return Console.ReadLine().Trim().Split(' ').Select(int.Parse).ToArray(); } static void rio(out int p1) { p1 = ri(); } static void rio(out int p1, out int p2) { var r = ria(2); p1 = r[0]; p2 = r[1]; } static void rio(out int p1, out int p2, out int p3) { var r = ria(3); p1 = r[0]; p2 = r[1]; p3 = r[2]; } static void rio(out int p1, out int p2, out int p3, out int p4) { var r = ria(4); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; } static void rio(out int p1, out int p2, out int p3, out int p4, out int p5) { var r = ria(5); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; p5 = r[4]; } static long rl() { return long.Parse(Console.ReadLine()); } static long[] rla(int n) { if (n <= 0) { Console.ReadLine(); return new long[0]; } else return Console.ReadLine().Trim().Split(' ').Select(long.Parse).ToArray(); } static void rlo(out long p1) { p1 = rl(); } static void rlo(out long p1, out long p2) { var r = rla(2); p1 = r[0]; p2 = r[1]; } static void rlo(out long p1, out long p2, out long p3) { var r = rla(3); p1 = r[0]; p2 = r[1]; p3 = r[2]; } static void rlo(out long p1, out long p2, out long p3, out long p4) { var r = rla(4); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; } static void rlo(out long p1, out long p2, out long p3, out long p4, out long p5) { var r = rla(5); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; p5 = r[4]; } static double rd() { return double.Parse(Console.ReadLine()); } static double[] rda(int n) { if (n <= 0) { Console.ReadLine(); return new double[0]; } else return Console.ReadLine().Trim().Split(' ').Select(double.Parse).ToArray(); } static void rdo(out double p1) { p1 = rd(); } static void rdo(out double p1, out double p2) { var r = rda(2); p1 = r[0]; p2 = r[1]; } static void rdo(out double p1, out double p2, out double p3) { var r = rda(3); p1 = r[0]; p2 = r[1]; p3 = r[2]; } static void rdo(out double p1, out double p2, out double p3, out double p4) { var r = rda(4); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; } static void rdo(out double p1, out double p2, out double p3, out double p4, out double p5) { var r = rda(5); p1 = r[0]; p2 = r[1]; p3 = r[2]; p4 = r[3]; p5 = r[4]; } static void swap(ref T x, ref T y) { T temp = x; x = y; y = temp; } static void wa1(T[] a) { Debug.WriteLine(string.Join(" ", a)); } static void wa2(T[][] a) { foreach (var row in a) { Debug.WriteLine(String.Join(" ", row)); } } [DebuggerDisplay("{x} , {y}")] class point { public int x, y; public point(int x, int y) { this.x = x; this.y = y; } } #endregion } static class Extention { public static T[][] ToJagArray(this T[,] a) { int n = a.GetLength(0), m = a.GetLength(1); var ret = new T[n][]; for (int i = 0; i < n; i++) { ret[i] = new T[m]; for (int j = 0; j < m; j++) { ret[i][j] = a[i, j]; } } return ret; } }