#include <bits/stdc++.h>
using namespace std;
const int oo = 1e9;
char grid[60][60];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = (0); i < (n); ++i)
    for (int j = (0); j < (m); ++j) cin >> grid[i][j];
  int ok = 1;
  for (int i1 = (0); i1 < (n); ++i1) {
    for (int i2 = (0); i2 < (i1); ++i2) {
      int a = 1, b = 1;
      for (int j = (0); j < (m); ++j) {
        if (grid[i1][j] == '#' && grid[i2][j] == '#') a = 0;
        if (grid[i1][j] != grid[i2][j]) b = 0;
      }
      ok &= (a || b);
    }
  }
  cout << (ok ? "Yes" : "No") << '\n';
  return 0;
}
