#include <bits/stdc++.h>
int main(void) {
  char grid[50][50];
  int h, w, i, j, cnt = 0;
  char newline[50];
  scanf("%d %d", &h, &w);
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      scanf("%c", &grid[i][j]);
    }
    scanf("%c", &newline[i]);
  }
  for (i = 0; i < h - 1; i++) {
    for (j = 0; j < w - 1; j++) {
      if (grid[i][j] == '#') {
        if (grid[i][j] != grid[i][j + 1] && grid[i][j] != grid[i + 1][j]) cnt++;
      }
    }
  }
  for (i = 0; i < h - 1; i++) {
    if (grid[i][w - 1] == '#') {
      if (grid[i][w - 1] != grid[i + 1][w - 1]) cnt++;
    }
  }
  for (j = 0; j < w - 1; j++) {
    if (grid[h - 1][j] == '#') {
      if (grid[h - 1][j] != grid[h - 1][j + 1]) cnt++;
    }
  }
  if (cnt > 0)
    printf("No");
  else
    printf("Yes");
  return 0;
}
