#include <bits/stdc++.h>
using namespace std;
int a[55][55];
int eq[55][55];
int n, m;
vector<int> v[55];
void check() {
  memset(eq, -1, sizeof eq);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      for (int k = 0; k < m; k++) {
        if (a[i][k] == a[j][k])
          continue;
        else {
          eq[i][j] = 0;
          break;
        }
      }
      if (eq[i][j] == -1) eq[i][j] = 1;
    }
  }
}
int main() {
  int i, j, ans = 1;
  char x;
  cin >> n >> m;
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++) {
      cin >> x;
      if (x == '#')
        a[i][j] = 1;
      else
        a[i][j] = 0;
    }
  }
  check();
  for (i = 0; i < m; i++) {
    for (j = 0; j < n; j++) {
      if (a[j][i] == 1) v[i].push_back(j);
    }
  }
  for (i = 0; i < m; i++) {
    for (j = 1; j < v[i].size(); j++) {
      if (eq[v[i][j]][v[i][0]])
        continue;
      else {
        ans = 0;
        break;
      }
    }
    if (ans == 0) break;
  }
  if (ans)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
