#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  cout.tie(0);
  int n, m;
  string s[51];
  vector<int> v;
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> s[i];
  for (int i = 0; i < n; i++) {
    v.clear();
    for (int j = 0; j < m; j++)
      if (s[i][j] == '#') v.push_back(j);
    for (int k = 1; k < v.size(); k++)
      for (int l = 0; l < n; l++)
        if (s[l][v[k]] != s[l][v[0]]) {
          cout << "No";
          return 0;
        }
  }
  cout << "Yes";
  return 0;
}
