import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.format;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;

alias sread = () => readln.chomp();
alias Point2 = Tuple!(long, "y", long, "x");

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void minAssign(T, U = T)(ref T dst, U src)
{
    dst = cast(T) min(dst, src);
}

void maxAssign(T, U = T)(ref T dst, U src)
{
    dst = cast(T) max(dst, src);
}

enum MOD = (10 ^^ 9) + 7;

void main()
{
    long H, W;
    scan(H, W);
    auto S = new string[](H);
    foreach (i; 0 .. H)
        S[i] = sread();
    foreach (y; 0 .. H)
        foreach (x; 0 .. W)
            if (S[y][x] == '#')
            {
                bool u = (0 < y) ? S[y - 1][x] == '#' : false;
                bool d = (y + 1 < H) ? S[y + 1][x] == '#' : false;
                bool l = (0 < x) ? S[y][x - 1] == '#' : false;
                bool r = (x + 1 < W) ? S[y][x + 1] == '#' : false;
                if (!(u || d || l || r))
                {
                    writeln("No");
                    return;
                }
            }
    writeln("Yes");
}
