#include <bits/stdc++.h>
int main() {
  int H, W, count = 0;
  char cs[50][50] = {"."};
  char ans[4] = "Yes";
  scanf("%d %d", &H, &W);
  for (int l = 0; l < H; l++) {
    scanf("%s", cs[l]);
  }
  for (int l = 0; l < H; l++) {
    for (int l2 = 0; l2 < W; l2++) {
      if (cs[l][l2] == '#') {
        if (l == 0 || cs[l - 1][l2] == '.') count++;
        if (l == H - 1 || cs[l + 1][l2] == '.') count++;
        if (l2 == 0 || cs[l][l2 - 1] == '.') count++;
        if (l2 == W - 1 || cs[l][l2 + 1] == '.') count++;
        if (count == 4) {
          strcpy(ans, "No");
        } else {
          strcpy(ans, "Yes");
        }
        count = 0;
      }
    }
  }
  printf("%s", ans);
  return 0;
}
