#include <bits/stdc++.h>
using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<long long>;
using vvl = vector<vl>;
using P = pair<long long, long long>;
using PP = pair<long long, P>;
using vp = vector<P>;
using vpp = vector<PP>;
using vs = vector<string>;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
const long long MOD = 1000000007LL;
const int INF = 1 << 30;
const long long LINF = 1LL << 60;
struct UnionFind {
  vi data;
  UnionFind(int size) : data(size, -1) {}
  bool unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x != y) {
      if (data[y] < data[x]) swap(x, y);
      data[x] += data[y];
      data[y] = x;
    }
    return x != y;
  }
  bool find(int x, int y) { return root(x) == root(y); }
  int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
  int size(int x) { return -data[root(x)]; }
};
int dx[] = {-1, 0, 1, 0}, dy[] = {0, -1, 0, 1};
int main() {
  int n, m;
  cin >> n >> m;
  vs vec(n);
  for (long long i = (0); i < (n); i++) {
    cin >> vec[i];
  }
  UnionFind uf(n * m);
  for (long long i = (0); i < (n); i++) {
    for (long long j = (0); j < (m); j++) {
      for (long long k = (0); k < (4); k++) {
        int x = i + dx[k];
        int y = j + dy[k];
        if (0 <= x && x < n && 0 <= y && y < m) {
          if (vec[i][j] == '#' && vec[x][y] == '#') {
            uf.unite(i * m + j, x * m + j);
          }
        }
      }
    }
  }
  for (long long i = (0); i < (n); i++) {
    for (long long j = (0); j < (m); j++) {
      if (vec[i][j] == '#' && uf.size(i * m + j) == 1) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
