#include <bits/stdc++.h>
using namespace std;
long long a[100];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; ++i) {
    string s;
    cin >> s;
    for (int j = 0; j < m; ++j) {
      if (s[j] == '#') a[i] += (1ll << (long long)j);
    }
  }
  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      if ((a[i] & a[j]) != 0 && a[i] != a[j]) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
