#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  char s[52][52] = {0};
  scanf("%d%d", &H, &W);
  for (int i = 1; i <= H; i++) scanf("%s", &s[i][1]);
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] == '#') continue;
        if (s[i + 1][j] == '#') continue;
        if (s[i][j - 1] == '#') continue;
        if (s[i][j + 1] == '#') continue;
        printf("NO\n");
        return 0;
      }
    }
  }
  printf("YES\n");
  return 0;
}
