#include <bits/stdc++.h>
int main(void) {
  int h, w, i, j, check = 1;
  scanf("%d%d", &h, &w);
  char color[52][52];
  for (i = 1; i < h + 1; i++) {
    for (j = 1; j < w + 1; j++) {
      scanf("%c", &color[i][j]);
    }
  }
  for (i = 1; i < h + 1; i++) {
    for (j = 1; j < w + 1; j++) {
      if (color[i][j] == '#') {
        if (color[i - 1][j] == '#' || color[i + 1][j] == '#' ||
            color[i][j - 1] == '#' || color[i][j + 1] == '#') {
          check = 1;
        } else {
          check = 0;
          break;
        }
      }
    }
    if (check == 0) {
      break;
    }
  }
  if (check == 1) {
    printf("Yes");
  } else {
    printf("No");
  }
  return 0;
}
