#include <bits/stdc++.h>
int main() {
  int h, w, i, j, k, l, flg = 0, a, b;
  char sin[55][55];
  int dx[4] = {1, 0, -1, 0}, dy[4] = {0, -1, 0, 1};
  scanf("%d%d", &h, &w);
  for (i = 0; i < h; i++) {
    for (j = 0; j <= w; j++) {
      scanf("%c", &sin[i][j]);
    }
  }
  for (k = 0; k < h; k++) {
    for (l = 0; l < w; l++) {
      printf("%c", sin[k][l]);
      if (sin[k][l] == '#') {
        for (i = 0; i < 4; i++) {
          a = k + dy[i];
          b = l + dx[i];
          if (a >= 0 && a < h && b >= 0 && b < w && sin[a][b] == '#') {
            flg = 1;
          }
        }
      }
    }
  }
  if (flg == 0) {
    printf("No\n");
  } else {
    printf("Yes\n");
  }
}
