#include <bits/stdc++.h>
using namespace std;
string a[55];
int n, m;
bool vis[55];
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> a[i];
  int flag = 0;
  for (int i = 0; i < n - 1; i++) {
    if (vis[i] == 1) continue;
    vis[i] = 1;
    int x = -1;
    for (int k = 0; k < m; k++) {
      if (a[i][k] == '#') {
        x = k;
        for (int j = i + 1; j < n; j++) {
          if (a[j][x] == a[i][x]) {
            if (a[j] != a[i]) {
              flag = 1;
              break;
            }
            vis[j] = 1;
          }
        }
      }
    }
    if (flag == 1) break;
  }
  if (flag)
    printf("No\n");
  else
    printf("Yes\n");
}
