#include <bits/stdc++.h>
#pragma optimize("Ofast")
using namespace std;
using ll = long long int;
using ull = unsigned long long int;
using dd = double;
using ldd = long double;
using si = short int;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
int main() {
  ios_base::sync_with_stdio(0);
  cout.tie(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<bitset<60>> arr(n + 1);
  char k;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      cin >> k;
      arr[i][j] = (k == '#');
    }
  }
  bool g = 1;
  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      if (arr[i] == arr[j] || (arr[i] & arr[j]) == arr.back()) continue;
      cout << "No";
      return 0;
    }
  }
  cout << "Yes";
  return 0;
}
