#include <bits/stdc++.h>
int main() {
  int H, W;
  scanf("%d %d", &H, &W);
  char can[H][W + 1];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j <= W; j++) {
      scanf("%c", &can[i][j]);
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 1; j <= W; j++) {
      if (can[i][j] == 35) {
        if (j == W || i == H - 1) continue;
        if (can[i][j + 1] == 35 || can[i + 1][j] == 35) continue;
        printf("No");
        return 0;
      }
    }
  }
  printf("Yes");
  return 0;
}
