#include <bits/stdc++.h>
using namespace std;
int main() {
  long long m, n, i, j, k, flag = 0, x;
  cin >> n >> m;
  char arr[n + 1][m + 1];
  for (i = 0; i < n; i++) cin >> arr[i];
  long long black[51];
  for (i = 0; i <= 50; i++) black[i] = 0;
  for (i = 0; i < n; i++) {
    x = -1;
    for (j = 0; j < m; j++) {
      if (arr[i][j] == '#') {
        if (black[j] == 0) {
          if (x == -1) {
            x = 1;
          }
          black[j] = i + 1;
        } else {
          if (x == -1) {
            for (k = 0; k < m; k++) {
              if (arr[black[j] - 1][k] != arr[i][k]) {
                flag = 1;
                break;
              }
            }
          } else {
            flag = 1;
            break;
          }
        }
      }
    }
  }
  if (flag == 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
