import std.algorithm;
import std.array;
import std.container;
import std.conv;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

bool calc(int h, int w, string[] ss) {
    foreach (r; 0..h) {
        foreach (c; 0..w) {
            if (ss[r][c] == '#') {
                int k = 1;
                if (r > 0 && ss[r-1][c] == '#') k++;
                if (r < h-1 && ss[r+1][c] == '#') k++;
                if (c > 0 && ss[r][c-1] == '#') k++;
                if (c < w-1 && ss[r][c+1] == '#') k++;

                if (k == 1) return false;
            }
        }
    }
    return true;
}

void main() {
    int h, w; scan(h, w);
    string[] ss;
    foreach (_; 0..h) ss ~= read!string;
    writeln(calc(h, w, ss) ? "Yes" : "No");
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;
