#include <bits/stdc++.h>
using namespace std;
char a[52][52];
int main() {
  int i, j, n, m;
  scanf("%d %d", &m, &n);
  for (i = 1; i <= m; i++)
    for (j = 1; j <= n; j++) scanf("%c", &a[i][j]);
  for (i = 1; i <= m; i++) {
    for (j = 1; j <= n; j++) {
      if (a[i - 1][j] == '.' && a[i + 1][j] == '.' && a[i][j - 1] == '.' &&
          a[i][j + 1] == '.') {
        printf("No");
        return 0;
      }
    }
  }
  printf("Yes");
  return 0;
}
