#include <bits/stdc++.h>
using namespace std;
template <class T>
void smin(T& a, T val) {
  if (a > val) a = val;
}
template <class T>
void smax(T& a, T val) {
  if (a < val) a = val;
}
template <typename T>
inline std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
  bool first = true;
  os << "[";
  for (auto i : v) {
    if (!first) os << ", ";
    os << i;
    first = false;
  }
  return os << "]";
}
const int MAX = 55;
void yes() { cout << "Yes"; }
void no() {
  cout << "No";
  exit(0);
}
char c[MAX][MAX];
int visit[MAX], n, m, siz[MAX];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m;
  for (int i = 1; i <= n; ++i)
    for (int j = 1; j <= m; ++j) cin >> c[i][j];
  int ans = 0;
  for (int i = 1; i <= n; ++i) {
    int ok1 = 0, ok2 = 0, cou = 0, tot = 0;
    for (int j = 1; j <= m; ++j)
      if (c[i][j] == '#') tot++;
    for (int j = 1; j <= m; ++j) {
      if (c[i][j] == '#') {
        if (!visit[j]) {
          visit[j] = 1;
          siz[j] = tot;
          ok1 = 1;
        } else if (visit[j]) {
          if (siz[j] != tot) cou = 1;
          ok2 = 1;
        }
      }
    }
    if (cou or (ok1 and ok2)) no();
  }
  yes();
  return 0;
}
