#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n, i, j, c;
  scanf("%d%d", &m, &n);
  getchar();
  char s[m][n];
  int p[m][n];
  for (i = 0; i < m; i++) {
    for (j = 0; j < n; j++) {
      scanf("%c", &s[i][j]);
      if (s[i][j] == '.')
        p[i][j] = 1;
      else
        p[i][j] = 0;
    }
    getchar();
  }
  for (i = 0; i < m; i++) {
    for (j = 0; j < n; j++) {
      if (j + 1 < n && s[i][j] == '#' && s[i][j + 1] == '#') {
        p[i][j] = 1;
        p[i][j + 1] = 1;
      }
      if (i + 1 < n && s[i][j] == '#' && s[i + 1][j] == '#') {
        p[i + 1][j] = 1;
        p[i][j] = 1;
      }
    }
  }
  for (i = 0, c = 1; i < m; i++) {
    for (j = 0; j < m; j++) {
      if (p[i][j] == 0) {
        c = 0;
        break;
      }
    }
  }
  if (c)
    printf("Yes\n");
  else
    printf("No\n");
  return 0;
}
