#include <bits/stdc++.h>
int main() {
  long H, W;
  std::cin >> H >> W;
  std::string s[52][52];
  for (long i = 0; i <= H + 1; i++) {
    for (long j = 0; j <= W + 1; j++) {
      s[i][j] = ".";
    }
  }
  for (long i = 1; i <= H; i++) {
    std::string temp;
    std::cin >> temp;
    for (long j = 1; j <= W; j++) {
      s[i][j] = temp[j];
    }
  }
  int flag = 1;
  for (long i = 1; i <= H; i++) {
    for (long j = 1; j <= W; j++) {
      if (s[i][j] == "#") {
        if (s[i - 1][j] != "#" && s[i + 1][j] != "#" && s[i][j - 1] != "#" &&
            s[i][j + 1] != "#") {
          flag = 0;
          break;
        }
      }
    }
    if (flag == 0) {
      break;
    }
  }
  if (flag == 1) {
    std::cout << "Yes" << std::endl;
  } else {
    std::cout << "No" << std::endl;
  }
  return 0;
}
