#include <bits/stdc++.h>
int main(void) {
  int H, W, cnt;
  scanf("%d %d", &H, &W);
  char masu[55][55];
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      scanf("%c", &masu[i][j]);
    }
  }
  for (int p = 1; p <= H; p++) {
    for (int q = 1; q <= W; q++) {
      if (masu[p][q] == '#' && masu[p][q - 1] != '#' && masu[p - 1][q] != '#' &&
          masu[p][q + 1] != '#' && masu[p + 1][q] != '#')
        cnt++;
    }
  }
  if (cnt == 0)
    printf("Yes");
  else
    printf("No");
  return 0;
}
