using System; using System.Collections.Generic; using System.Linq; class Program { static void Main(string[] args) { var H = sc.ReadInt(); var W = sc.ReadInt(); var S = sc.ReadStrArray(H); var count = S.Aggregate(0, (c, s) => c + s.Count(ch => ch == '#')); if (count % 2 == 1) { Console.WriteLine("NO"); return; } for (int dh = -H; dh < H; dh++) { for (int dw = -W; dw < W; dw++) { if (dh == 0 && dw == 0) continue; var t = new int[H, W]; for (int i = 0; i < H; i++) { for (int j = 0; j < W; j++) { if (S[i][j] == '#') { // 平行移動の大きさとして不適当 var h = i + dh; var w = j + dw; if (h < 0 || H <= h) continue; if (w < 0 || W <= w) continue; if (t[i, j] == 0 && t[h, w] == 0 && S[h][w] == '#') { t[i, j] = 1; t[h, w] = 2; } } } } var ok = true; for (int i = 0; i < H; i++) { for (int j = 0; j < W; j++) { if (S[i][j] == '#' && t[i, j] == 0) ok = false; } } if (ok) { Console.WriteLine("YES"); //Console.WriteLine(dh + " " + dw); return; } } } Console.WriteLine("NO"); } static Scanner sc = new Scanner(); } class Scanner { string[] S = new string[0]; int Index = 0; char[] Separators = new char[] { ' ' }; public string Next() { if (this.Index < this.S.Length) return this.S[this.Index++]; var line = ""; while (line == "") line = Console.ReadLine(); this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries); if (this.S.Length == 0) return this.Next(); this.Index = 0; return this.S[this.Index++]; } public string ReadStr() { return this.Next(); } public char ReadChar() { return this.Next()[0]; } public int ReadInt() { return int.Parse(this.Next()); } public uint ReadUInt() { return uint.Parse(this.Next()); } public long ReadLong() { return long.Parse(this.Next()); } public double ReadDouble() { return double.Parse(this.Next()); } public Tuple ReadTup(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add); } public Tuple ReadTupLong(int add = 0) { return Tuple.Create(this.ReadLong() + add, this.ReadLong() + add); } public Tuple ReadTup3(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add); } public Tuple ReadTup4(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add); } public int[] ReadIntArray(int n) { var array = new int[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadInt(); } return array; } public long[] ReadLongArray(int n) { var array = new long[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadLong(); } return array; } public double[] ReadDoubleArray(int n) { var array = new double[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadDouble(); } return array; } public char[] ReadCharArray(int n) { var array = new char[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadChar(); } return array; } public string[] ReadStrArray(int n) { var array = new string[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadStr(); } return array; } public Tuple[] ReadTupLongArray(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTupLong(add); } return array; } public Tuple[] ReadTupArray(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup(add); } return array; } public Tuple[] ReadTup3Array(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup3(add); } return array; } public Tuple[] ReadTup4Array(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup4(add); } return array; } }