#include <bits/stdc++.h>
using namespace std;
const int maxN = 55;
int a[maxN][maxN];
int main() {
  ios_base::sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; ++i) {
    string s;
    cin >> s;
    for (int j = 1; j <= m; ++j) {
      if (s[j - 1] == '.')
        a[i][j] = 0;
      else
        a[i][j] = 1;
    }
  }
  bool ok = true;
  for (int i = 1; i <= n; ++i) {
    bool emp = true;
    int sz = 0;
    for (int j = 1; j <= m; ++j) {
      if (a[i][j] == 1) emp = false, ++sz;
    }
    if (emp) continue;
    for (int k = i + 1; k <= n; ++k) {
      bool good = true;
      int t = 0, t2 = 0;
      for (int j = 1; j <= m; ++j) {
        if (a[i][j] == a[k][j] && a[i][j] == 1) {
          good = false;
          ++t;
        } else if (a[i][j] != a[k][j])
          ++t2;
      }
      if (good) continue;
      if (!good) {
        if (t == sz && t2 == 0) {
          continue;
        } else {
          ok = false;
        }
      }
    }
  }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
