#include <bits/stdc++.h>
using namespace std;
char board[55][55];
int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};
int main() {
  int H, W;
  scanf("%d%d", &H, &W);
  for (int i = 1; i <= H; i++) {
    getchar();
    for (int j = 1; j <= W; j++) {
      scanf("%c", &board[i][j]);
    }
  }
  bool flag = true;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (board[i][j] == '#') {
        bool ok = false;
        for (int k = 0; k < 4; k++) {
          int nx = i + dx[k];
          int ny = j + dy[k];
          if (nx > 0 && ny > 0 && nx <= H && ny <= W && board[nx][ny] == '#')
            ok = true;
        }
        flag = ok;
      }
    }
  }
  if (flag)
    printf("Yes");
  else
    printf("No");
  return 0;
}
