#include <bits/stdc++.h>
int main(void) {
  int h, w;
  int count;
  char box[60][60];
  int h1 = scanf("%d", &h);
  int w1 = scanf("%d\n", &w);
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      char box1 = scanf("%s", &box[i][j]);
    }
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (box[i][j] == '#' && box[i + 1][j] != '#' && box[i - 1][j] != '#' &&
          box[i][j - 1] != '#' && box[i][j + 1] != '#') {
        count++;
      }
    }
  }
  if (count == 0) {
    printf("Yes");
  } else {
    printf("No");
  }
  return 0;
}
