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