#include <bits/stdc++.h>
using namespace std;
int n, m;
vector<string> v;
bool used[55];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) {
    string s;
    cin >> s;
    v.push_back(s);
  }
  sort(v.begin(), v.end());
  v.erase(unique(v.begin(), v.end()), v.end());
  int yes = 1;
  for (int i = 0; i < v.size(); i++) {
    for (int j = 0; j < m; j++) {
      if (v[i][j] == '#') {
        if (used[j]) {
          yes = 0;
          break;
        }
        used[j] = 1;
      }
    }
  }
  if (yes)
    printf("Yes");
  else
    printf("No");
  return 0;
}
