#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[55][55];
  int h, w;
  while (~scanf("%d%d", &h, &w)) {
    for (int i = 0; i < w; i++) {
      for (int j = 0; j < h; j++) {
        scanf("%c", &s[i][j]);
      }
      getchar();
    }
    int flag = 1;
    for (int i = 0; i < w; i++) {
      for (int j = 0; j < h; j++) {
        if (s[i][j] == '#') {
          if (s[i][j + 1] == '#' || s[i][j - 1] == '#' || s[i + 1][j] == '#' ||
              s[i - 1][j] == '#')
            flag = 1;
          else {
            flag = 0;
            break;
          }
        }
      }
      if (flag == 0) break;
    }
    printf(flag ? "Yes\n" : "No\n");
  }
  return 0;
}
