#include <bits/stdc++.h>
using namespace std;
char alphz[27] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
                  'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
                  's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
float Euclidean(long long x1, long long x2, long long y1, long long y2) {
  return sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2));
}
long long GCD(long long a, long long b) { return !b ? a : GCD(b, a % b); }
long long LCM(long long a, long long b) { return (a * b) / GCD(a, b); }
void PrimeFactor(long long n) {
  while (n % 2 == 0) {
    n /= 2;
  }
  for (int i = 3; i <= sqrt(n); i += 2) {
    if (n % i == 0) {
      n /= i;
    }
  }
  if (n > 2) {
  };
}
bool Is_Square(long long x) {
  long long l = 0, r = x;
  while (l <= r) {
    long long mid = l + (r - l) / 2;
    if (mid * mid == x) return true;
    if (mid * mid > x)
      r = mid - 1;
    else
      l = mid + 1;
  }
  return false;
}
long long Power(long long x, long long y) {
  long long temp;
  if (y == 0) return 1;
  temp = Power(x, y / 2);
  if (y % 2 == 0)
    return temp * temp;
  else
    return x * temp * temp;
}
bool Is_Prime(int x) {
  if (x == 2)
    return 1;
  else if (x % 2 == 0 || x < 2)
    return 0;
  for (int i = 3; i * i <= x; i += 2)
    if (x % i == 0) return 0;
  return 1;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int r, h;
  cin >> r >> h;
  vector<vector<char>> a(r, vector<char>(h));
  for (int i = 0; i < r; i++) {
    for (int j = 0; j < h; j++) cin >> a[i][j];
  }
  int ok = 0;
  for (int i = 0; i < r; i++) {
    for (int j = 0; j < h; j++) {
      if (a[i][j] == '#' && a[i + 1][j] != '#' && a[i - 1][j] != '#' &&
          a[i][j - 1] == '#' && a[i][j + 1] == '#') {
        ok |= 1;
        break;
      }
    }
  }
  if (ok)
    cout << "Yes\n";
  else
    cout << "No\n";
  return 0;
}
