#include <bits/stdc++.h>
using namespace std;
const long long inf = 1ll << 50;
const int maxN = 60;
char a[maxN][maxN];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int b[maxN][maxN];
int main() {
  int h, w;
  scanf("%d %d", &h, &w);
  for (int i = 1; i <= h; i++) {
    scanf("%s", &a[i] + 1);
  }
  int flag = 0;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      int sum = 0;
      if (a[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int ti = i + dx[k];
          int tj = j + dy[k];
          if (ti >= 1 && tj >= 1) {
            if (a[ti][tj] == '#') sum++;
          }
        }
      }
      if (sum == 0 && a[i][j] == '#') {
        printf("No\n");
        return 0;
      }
    }
  }
  printf("Yes\n");
  return 0;
}
