#include <bits/stdc++.h>
using namespace std;
int a[55][55];
int h, w;
int main() {
  memset(a, 0, sizeof(a));
  scanf("%d%d", &h, &w);
  getchar();
  for (int i = 1; i <= w; i++) {
    for (int j = 1; j <= h; j++) {
      char c = getchar();
      if (c == '#') {
        a[i][j] = 1;
      } else
        a[i][j] = 2;
    }
    getchar();
  }
  for (int i = 1; i <= w; i++) {
    for (int j = 1; j <= h; j++) {
      if (a[i][j] == 1) {
        if (!((a[i][j] == a[i][j + 1]) || (a[i][j] == a[i][j - 1]) ||
              (a[i][j] == a[i - 1][j]) || (a[i][j] == a[i + 1][j]))) {
          printf("No");
          return 0;
        }
      }
    }
  }
  printf("Yes");
  return 0;
}
