#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m;
  cin >> n >> m;
  vector<vector<int> > a(n, vector<int>(m, 0));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      char t;
      cin >> t;
      if (t == '#')
        a[i][j] = 1;
      else
        a[i][j] = 0;
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      int intersect = true, same = 1;
      for (int k = 0; k < m; k++) {
        if (a[i][k] != a[j][k]) same = 0;
        if (a[i][k] && a[j][k]) intersect = 0;
      }
      if (!same && !intersect) {
        cout << "No\n";
        exit(0);
      }
    }
  }
  cout << "Yes\n";
  return 0;
}
