#include <bits/stdc++.h>
using namespace std;
static const int MAXN = 50 + 5;
string r[MAXN], c[MAXN];
int n, m;
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> r[i];
  for (int i = 0; i < m; i++)
    for (int j = 0; j < n; j++) c[i] = c[i] + r[j][i];
  for (int i = 0; i < n; i++) {
    set<int> S;
    for (int j = 0; j < m; j++) {
      if (r[i][j] == '#') S.insert(j);
    }
    for (auto it : S) {
      if (c[it] == c[*S.begin()])
        continue;
      else {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
