#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W, N;
  N = 0;
  cin >> H >> W;
  char s[H][W];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < W; i++) {
    if (s[H][i] == '#') {
      if (!(s[H][i + 1] == '#')) N = 1;
    }
  }
  for (int i = 0; i < H; i++) {
    if (s[i][W] == '#') {
      if (!(s[i + 1][W] == '#')) N = 1;
    }
  }
  for (int i = 0; i < H - 1; i++) {
    for (int j = 0; j < W - 1; j++) {
      if (s[i][j] == '#') {
        if (!(s[i][j + 1] == '#' || s[i + 1][j] == '#')) N = 1;
      }
    }
  }
  if (N == 1) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}
