#include <bits/stdc++.h>
using namespace std;
const long long INF = LLONG_MAX;
const long long MOD = 1e9 + 7;
long long H, W;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> H >> W;
  long long s[50][50];
  for (long long i = 0; i < H; ++i) {
    for (long long j = 0; j < W; ++j) {
      cin >> s[i][j];
    }
  }
  for (long long i = 0; i < H; ++i) {
    for (long long j = 0; j < W; ++j) {
      if (s[i][j] == '#') {
        if (s[i + 1][j] == '.' || s[i - 1][j] == '.' || s[i][j + 1] == '.' ||
            s[i][j - 1] == '.') {
          puts("No");
          return 0;
        }
      }
    }
  }
  puts("Yes");
}
