#include <bits/stdc++.h>
int main() {
  int H, W, i, j, ans;
  ans = 1;
  scanf("%d%d", &H, &W);
  char S[H + 2][W + 2];
  for (i = 0; i < W + 2; i = i + 1) {
    S[0][i] = '.';
    S[H + 1][i] = '.';
  }
  for (i = 0; i < H + 2; i = i + 1) {
    S[i][0] = '.';
    S[i][W + 1] = '.';
  }
  for (i = 1; i < H + 2; i = i + 1) {
    for (j = 1; j < W + 1; j = j + 1) {
      scanf("%c", &S[i][j]);
    }
  }
  for (i = 1; i < H + 1; i = i + 1) {
    for (j = 1; j < W + 1; j = j + 1) {
      if ((S[i - 1][j] == '.') && (S[i + 1][j] == '.') &&
          (S[i][j - 1] == '.') && (S[i][j + 1] == '.')) {
        ans = 0;
      }
    }
  }
  if (ans == 1) {
    printf("No\n");
  }
  if (ans == 0) {
    printf("Yes\n");
  }
  return 0;
}
