#include <bits/stdc++.h>
using namespace std;
int main() {
  int rows, cols;
  cin >> rows >> cols;
  vector<string> config;
  string row;
  for (int i = 0; i < rows; ++i) {
    cin >> row;
    config.push_back(row);
  }
  for (int i = 0; i < rows; ++i)
    for (int j = i + 1; j < rows; ++j) {
      int flag = 0;
      int equal_flag = 1;
      for (int k = 0; k < cols; ++k) {
        if (config[i][k] != config[j][k] && equal_flag == 1) {
          equal_flag = 0;
        }
        if (config[i][k] == '#' && config[j][k] == '#' && flag != 1) {
          flag = 1;
        }
        if (flag == 1 && equal_flag == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  cout << "Yes" << endl;
}
