#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  char a[n + 1][m + 1];
  vector<long long int> v[n + 1], v1[m + 1];
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      cin >> a[i][j];
    }
  }
  int flag = 0, cnt, cnt1;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      cnt = 0;
      cnt1 = 0;
      if (i != j) {
        for (int k = 1; k <= m; k++) {
          if (a[i][k] == a[j][k] && a[i][k] == '#')
            cnt = 1;
          else if (a[i][k] == '#' || a[j][k] == '#')
            cnt1 = 1;
        }
      }
      if (cnt == 1 && cnt1 == 1) flag = 1;
    }
  }
  if (flag)
    cout << "No";
  else
    cout << "Yes";
}
