#include <bits/stdc++.h>
int Y[] = {1, 0, -1, 0};
int X[] = {0, 1, 0, -1};
int main() {
  int w, h, i, j, k;
  char s[110][110] = {};
  scanf("%d %d", &h, &w);
  for (i = 0; i < h; i++) scanf("%s", s[i + 1] + 1);
  for (i = 1; i <= h; i++) {
    for (j = 1; j <= w; j++) {
      if (s[i][j] - '#') continue;
      for (k = 0; k < 4; k++) {
        if (s[i + Y[k]][j + X[k]] == '#') goto NEXT;
      }
      printf("No\n");
      return 0;
    }
  NEXT:;
  }
  printf("Yes\n");
  return 0;
}
