#include <bits/stdc++.h>
int main() {
  int H, W;
  char S[55][55];
  scanf("%d%d", &H, &W);
  for (int i = 0; i < H; i++) {
    scanf("%s", S[i]);
  }
  int f, ft;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') {
        if (S[i][j - 1] == '#' || S[i][j + 1] == '#' || S[i - 1][j] == '#' ||
            S[i + 1][j] == '#') {
          f = 1;
        } else
          f = 0;
        ft = f;
      }
      ft *= ft;
    }
  }
  if (ft == 1)
    puts("Yes");
  else
    puts("No");
  return 0;
}
