#include <bits/stdc++.h>
using namespace std;
const int N = 55;
int n, m;
char mp[N][N];
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) cin >> mp[i][j];
  bool f = 1;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++)
      for (int ii = i + 1; ii <= n; ii++)
        for (int jj = j + 1; jj <= m; jj++) {
          if (mp[i][j] == '#' && mp[i][jj] == '#' && mp[ii][jj] == '#' &&
              mp[ii][j] != '#')
            f = 0;
          if (mp[i][j] == '#' && mp[ii][j] == '#' && mp[ii][jj] == '#' &&
              mp[i][jj] != '#')
            f = 0;
          if (mp[ii][j] == '#' && mp[i][jj] == '#' && mp[ii][jj] == '#' &&
              mp[i][j] != '#')
            f = 0;
          if (mp[i][j] == '#' && mp[i][jj] == '#' && mp[ii][j] == '#' &&
              mp[ii][jj] != '#')
            f = 0;
        }
  if (f)
    cout << "Yes\n";
  else
    cout << "No\n";
  return 0;
}
