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

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] lreads(T = long)(long n){return generate(()=>readln.chomp.to!T()).take(n).array();}
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;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long H, W;
    scan(H, W);
    auto S = new string[](H);
    foreach (i; 0 .. H)
        S[i] = sread();
    foreach (h; 0 .. H)
        foreach (w; 0 .. W)
            if (S[h][w] == '#')
            {
                if (0 < h && S[h - 1][w] == '#')
                    continue;
                if (h + 1 < H && S[h + 1][w] == '#')
                    continue;
                if (0 < w && S[h][w - 1] == '#')
                    continue;
                if (w + 1 < W && S[h][w + 1] == '#')
                    continue;
                writeln("No");
                return;
            }
    writeln("Yes");
}
