#include <bits/stdc++.h>
using namespace std;
int a[50][50];
int main() {
  int n, k;
  cin >> n >> k;
  char g[n][k];
  for (int j = 0; j < n; j++) {
    for (int i = 0; i < k; i++) {
      cin >> g[i][j];
      if (g[i][j] == '#') a[i][j] = 1;
    }
    for (int i = 0; i < k - 1; i++) {
      if (a[i][j] >= 1 and a[i + 1][j] >= 1) {
        a[i][j]++;
        a[i + 1][j]++;
      }
    }
  }
  for (int i = 0; i < k; i++) {
    for (int j = 0; j < n - 1; j++) {
      if (a[i][j] >= 1 and a[i][j + 1] >= 1) {
        a[i][j]++;
        a[i][j + 1]++;
      }
    }
  }
  for (int j = 0; j < n; j++) {
    for (int i = 0; i < k; i++) {
      if (a[i][j] == 1) {
        cout << "No";
        system("pause");
        return 0;
      }
    }
  }
  cout << "Yes";
  system("pause");
  return 0;
}
