<?php
fscanf(STDIN,"%d %d",$h,$w); // 1 2
//$k_num = trim(fgets(STDIN)); //数字や文字列

//0行目に壁
$pre_input = ".";
for ($i = 0; $i < $w-1; $i++) {
     $pre_input = $pre_input.".";
}
$map[0] = preg_split("//", $pre_input );

for ($i = 1; $i <= $h ; $i++) {
    $input_row = trim(fgets(STDIN));
        $map[$i] = preg_split("//", $input_row );
}

//最終行に壁
$pre_input = ".";
for ($i = 0; $i < $w-1; $i++) {
     $pre_input = $pre_input.".";
}
$map[$h+1] = preg_split("//", $pre_input );

//＃があれば1にする
$flag_sharp = 0;
for ($row = 1; $row <= $h; $row++) {
    for ($column = 1; $column <= $w; $column++) {
         if ( $map[$row][$column] == "#" ) {
             $flag_sharp = 1;
             //echo($row."/".$column."\n");
             //上下左右に＃がなければNo
             if ( $map[$row-1][$column] != "#" &&
                  $map[$row][$column-1] != "#" &&
                  $map[$row][$column+1] != "#" &&
                  $map[$row+1][$column] != "#") {
                exit("No");
             }
         }
         //echo("*".$row."/".$column.":".$map[$row][$column]."\n");
    }
}

//＃がなければNoを表示
if ( $flag_sharp == 0) {
    echo("No");
}else {
    echo("Yes");
}
?>