#include <bits/stdc++.h>
int main(void) {
  int h, w, flag;
  scanf("%d %d", &h, &w);
  char grid[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      scanf("%c", &(grid[i][j]));
    }
  }
  flag = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (grid[i][j] == '.') continue;
      if (i != 0) {
        if (grid[i - 1][j] == '#') continue;
      }
      if (i != h - 1) {
        if (grid[i + 1][j] == '#') continue;
      }
      if (j != 0) {
        if (grid[i][j - 1] == '#') continue;
      }
      if (j != w - 1) {
        if (grid[i][j + 1] == '#') continue;
      }
      flag = 1;
      break;
    }
    if (flag) break;
  }
  if (flag) {
    printf("No");
  } else {
    printf("Yes");
  }
}
