#include <bits/stdc++.h>
using namespace std;
map<string, int> mp;
int main() {
  int n, m;
  cin >> n >> m;
  char a[n][m];
  for (int i = 0; i < n; i++) {
    string s;
    cin >> s;
    if (mp.find(s) == mp.end()) mp[s] = i;
  }
  int fl = 0;
  int col[100] = {0};
  map<string, int>::iterator it;
  for (it = mp.begin(); it != mp.end(); it++) {
    string s = it->first;
    for (int i = 0; i < s.length(); i++) {
      if (s[i] == '#' && col[i] == true)
        fl = 1;
      else if (s[i] == '#')
        col[i] = true;
    }
  }
  if (fl)
    cout << "No\n";
  else
    cout << "Yes\n";
  return 0;
}
