#include <bits/stdc++.h>
using namespace std;
int dsu[1000005];
int size[1000005];
int search(int a) {
  if (dsu[a] == a) return a;
  return dsu[a] = search(dsu[a]);
}
void join(int a, int b) {
  a = search(a);
  b = search(b);
  if (size[a] < size[b]) {
    dsu[b] = a;
    size[a] += size[b];
  } else {
    dsu[a] = b;
    size[b] += size[a];
  }
}
void solve() {
  int n, m;
  cin >> n >> m;
  string s[n];
  for (int i = 0; i < m * n; i++) {
    size[i] = 1;
    dsu[i] = i;
  }
  for (int i = 0; i < n; i++) cin >> s[i];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (j + 1 < m && s[i][j] == '#' && s[i][j + 1] == '#') {
        if (search(((i) * (m) + (j))) != search(((i) * (m) + (j + 1))))
          join(((i) * (m) + (j)), ((i) * (m) + (j + 1)));
      }
      if (i + 1 < n && s[i][j] == '#' && s[i + 1][j] == '#') {
        if (search(((i) * (m) + (j))) != search(((i + 1) * (m) + (j))))
          join(((i) * (m) + (j)), ((i + 1) * (m) + (j)));
      }
    }
  }
  bool f = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '#') {
        if (size[search(((i) * (m) + (j)))] == 1) {
          f = 1;
          break;
        }
      }
    }
  }
  if (f)
    cout << "No\n";
  else
    cout << "Yes\n";
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  for (int i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
