#include <bits/stdc++.h>
int main() {
  int h, w, i, j;
  char s[52][52];
  for (i = 0; i < 52; i++) {
    for (j = 0; j < 52; j++) {
      s[i][j] = '.';
    }
  }
  scanf("%d %d", &h, &w);
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      scanf("%c", &s[i + 1][j + 1]);
    }
  }
  for (i = 1; i <= h; i++) {
    for (j = 1; j <= w; j++) {
      if (s[i][j] == '#') {
        if (s[i][j] != s[i - 1][j] && s[i][j] != s[i + 1][j] &&
            s[i][j] != s[i][j - 1] && s[i][j] != s[i][j + 1])
          break;
      }
    }
    if (j == w) break;
  }
  if (i == h) {
    printf("Yes\n");
  } else {
    printf("No\n");
  }
}
