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