#include <bits/stdc++.h>
using namespace std;
int h, w, startx, starty;
char m[51][51];
int dx[] = {0, 0, -1, 1};
int dy[] = {1, -1, 0, 0};
void f(int i, int j) {
  if (m[i][j] == '#') m[i][j] = '.';
  for (int k = 0; k < 4; k++) {
    int nx = i + dx[k];
    int ny = j + dy[k];
    if (1 <= nx && nx <= h && 1 <= ny && ny <= w && m[nx][ny] == '#') f(nx, ny);
  }
}
bool allWhite() {
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      if (m[i][j] == '#') return false;
    }
  return true;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> h >> w;
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      cin >> m[i][j];
      if (m[i][j] == '#') {
        startx = i;
        starty = j;
      }
    }
  f(startx, starty);
  if (allWhite())
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
