#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  string grid[n];
  for (int i = 0; i < n; i++) {
    cin >> grid[i];
  }
  vector<bool> checked(n);
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      bool same = true, intersection = false;
      for (int k = 0; k < m; k++) {
        same &= grid[i][k] == grid[j][k];
        intersection |= grid[i][k] == '#' && grid[j][k] == '#';
      }
      if (!same && intersection) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
}
