// dfmt off
T lread(T=long)(){return readln.chomp.to!T;}T[] lreads(T=long)(long n){return iota(n).map!((_)=>lread!T).array;}
T[] aryread(T=long)(){return readln.split.to!(T[]);}void arywrite(T)(T a){a.map!text.join(' ').writeln;}
void scan(L...)(ref L A){auto l=readln.split;foreach(i,T;L){A[i]=l[i].to!T;}}alias sread=()=>readln.chomp();
void dprint(L...)(lazy L A){debug{auto l=new string[](L.length);static foreach(i,a;A)l[i]=a.text;arywrite(l);}}
static immutable MOD=10^^9+7;alias PQueue(T,alias l="b<a")=BinaryHeap!(Array!T,l);import std;
// 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");
}
