#include <bits/stdc++.h>
int main() {
  int h, w;
  scanf("%d %d", &h, &w);
  char b[52][52] = {};
  char temp[64];
  for (int i = 1; i <= h; ++i) {
    scanf("%s", temp);
    for (int j = 1; j <= w; ++j) {
      if (temp[j] == '#') {
        b[i][j] = 1;
      }
    }
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (b[i][j]) {
        if (!(b[i - 1][j] || b[i + 1][j] || b[i][j - 1] || b[i][j + 1])) {
          printf("No\n");
          return 0;
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
