#include <bits/stdc++.h>
using namespace std;
bool cols[100];
int main() {
  int n, m;
  cin >> n >> m;
  set<string> rows;
  string ans = "Yes";
  for (int _i = 0; _i < n; _i++) {
    string t;
    cin >> t;
    rows.insert(t);
  }
  for_each(rows.begin(), rows.end(), [&](string r) {
    for (int _i = 0; _i < r.size(); _i++) {
      if (r[_i] == '#') {
        if (!cols[_i]) {
          cols[_i] = true;
        } else {
          ans = "No";
        }
      }
    }
  });
  cout << ans << endl;
}
