#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int H, W;
  cin >> H >> W;
  const int dx[4] = {0, 0, -1, 1};
  const int dy[4] = {-1, 1, 0, 0};
  std::vector<std::vector<char>> graph(H, std::vector<char>(W));
  for (int i = 0; i < (H); i++) {
    for (int j = 0; j < (W); j++) {
      cin >> graph[i][j];
    }
  }
  bool can = true;
  for (int i = 0; i < W; i++) {
    for (int j = 0; j < H; j++) {
      if (graph[i][j] == '.') continue;
      bool exist = false;
    }
  }
  if (can) {
    std::cout << "Yes" << std::endl;
  } else {
    std::cout << "No" << std::endl;
  }
  return 0;
}
