#include <bits/stdc++.h>
using namespace std;
int n, m;
long long a[60];
char s[60];
int main() {
  int i, j;
  cin >> n >> m;
  for (i = 1; i <= n; ++i) {
    scanf("%s", s + 1);
    for (j = 1; j <= m; ++j) a[i] = (a[i] << 1 | (s[j] == '#'));
  }
  for (i = 1; i <= n; i++)
    for (j = i + 1; j <= n; j++)
      if ((a[i] != a[j]) && (a[i] & a[j])) {
        cout << "No";
        return 0;
      }
  cout << "Yes";
  return 0;
}
