#include <bits/stdc++.h>
using namespace std;
int line[100];
int vis[100];
int main() {
  int n, m;
  cin >> n >> m;
  string s[100];
  for (int i = 0; i < n; i++) cin >> s[i];
  int flag = 0;
  for (int i = 0; i < n; i++) {
    if (vis[i] == 1) continue;
    for (int j = i + 1; j < n; j++) {
      if (vis[j] == 1) continue;
      if (s[i] == s[j]) vis[j] = 1;
    }
    for (int k = 0; k < m; k++)
      if (s[i][k] == '#') {
        if (line[k] == 1) {
          flag = 1;
          break;
        }
        line[k] = 1;
      }
    if (flag == 1) break;
  }
  if (flag == 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
