#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<string> a(n);
  for (int i = 0; i < (int)(n); i++) {
    cin >> a[i];
  }
  bool bad = false;
  for (int i = 0; i < (int)(n); i++) {
    for (int j = 0; j < (int)(m); j++) {
      if (a[i][j] == '#') {
        for (int k = 0; k < (int)(n); k++) {
          if (k == i) continue;
          for (int t = 0; t < (int)(m); t++) {
            if (t == j) continue;
            int cnt = 1;
            if (a[i][t] == '#') cnt++;
            if (a[k][j] == '#') cnt++;
            if (a[k][t] == '#') cnt++;
            if (cnt == 3) bad = true;
          }
        }
      }
    }
  }
  if (!bad) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
