#include <bits/stdc++.h>
int main() {
  int H, W;
  scanf("%d %d", &H, &W);
  char s[52][52] = {{0}};
  for (int i = 1; i <= H; i++) scanf("%s", s[i] + 1);
  for (int i = 1; i <= H; i++)
    for (int j = 1; j <= W; j++)
      if (s[i][j] == '#' && s[i][j + 1] != '#' && s[i][j - 1] != '#' &&
          s[i - 1][j] != '#' && s[i + 1][j] != '#') {
        printf("No\n");
        return 0;
      }
  printf("Yes\n");
  return 0;
}
