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