#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 1;
set<string> s;
vector<int> g[maxn];
vector<int> gr[maxn];
bool used[100];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    string t;
    cin >> t;
    s.insert(t);
  }
  for (int i = 0; i < m; ++i) {
    int cnt = 0;
    for (auto it : s)
      if (it[i] == '#') ++cnt;
    if (cnt > 1) {
      cout << "No";
      return 0;
    }
  }
  cout << "Yes";
}
