#include <bits/stdc++.h>
int main(void) {
  int h, w, i, j, k = 0, l = 0;
  char s[51][51];
  scanf("%d %d", &h, &w);
  for (i = 1; i <= h + 1; i++) {
    for (j = 1; j <= w; j++) {
      scanf("%c", &s[i][j]);
    }
  }
  for (i = 0; i < h + 1; i++) {
    for (j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        k += 1;
        if (s[i][j] == s[i - 1][j] || s[i][j] == s[i + 1][j] ||
            s[i][j] == s[i][j - 1] || s[i][j] == s[i][j + 1]) {
          l += 1;
        } else {
          l = l;
        }
      }
    }
  }
  if (k == l) {
    printf("Yes\n");
  } else {
    printf("No\n");
  }
  return 0;
}
