#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n;
  cin >> n;
  cin >> m;
  vector<string> grid(n);
  vector<bool> cols(m, false);
  for (int i = 0; i < n; i++) cin >> grid[i];
  sort(grid.begin(), grid.end());
  grid.resize(unique(grid.begin(), grid.end()) - grid.begin());
  for (int i = 0; i < grid.size(); i++) {
    for (int j = 0; j < m; j++) {
      if (grid[i][j] == '#') {
        if (cols[j]) {
          cout << "No" << endl;
          return 0;
        }
        cols[j] = true;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
