#include <bits/stdc++.h>
using namespace std;
int djs[3000];
int par(int n) { return djs[n] == n ? n : djs[n] = par(djs[n]); }
int merge(int a, int b) { djs[par(a)] = par(b); }
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  int x, c = 0;
  for (int i = 0; i < h; ++i) {
    cin >> s[i];
    for (int j = 0; j < w; ++j) {
      djs[i * w + j] = i * w + j;
      if (s[i][j] == '#') {
        ++c;
        x = i * w + j;
        if (j && s[i][j - 1] == '#') merge(i * w + j, i * w + j - 1);
        if (i && s[i - 1][j] == '#') merge(i * w + j, (i - 1) * w + j);
      }
    }
  }
  for (int i = 0; i < h; ++i)
    for (int j = 0; j < w; ++j)
      if (c == 1 || (s[i][j] == '#' && par(i * w + j) != par(x))) {
        cout << "No\n";
        return 0;
      }
  cout << "Yes\n";
}
