#include <bits/stdc++.h>
using namespace std;
int main() {
  string a[50];
  int n, k, i, j, t;
  bool flag = true;
  cin >> n >> k;
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < n; i++) {
    for (j = 0; j < k; j++) {
      if (a[i][j] == '#') {
        for (t = i + 1; t < n; t++) {
          if (a[t][j] == '#') {
            if (a[t] != a[i]) {
              flag = false;
              break;
            }
          }
        }
      }
    }
  }
  if (flag == true)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
