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