#include <bits/stdc++.h>
using namespace std;
int h, w;
char arr[55][55], trash;
int main(void) {
  scanf("%d %d", &h, &w);
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) scanf("%c", &arr[i][j]);
    scanf("%c", &trash);
  }
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++)
      if (arr[i][j] == '#')
        if ((arr[i - 1][j] == '#' || arr[i + 1][j] == '#' ||
             arr[i][j - 1] == '#' || arr[i][j + 1] == '#'))
          continue;
        else
          return !printf("No");
  printf("Yes");
}
