#include <cstdio>
#include <iostream>
using namespace std;

int H, W;
char c[55][55];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};

int main() {
	cin >> H >> W;
	for (int i = 0; i < H; i++) {
        scanf("%s", &s[i]);
	}
    bool ans = true;
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (s[i][j] = '#') {
                bool found = false;
                for (int k = 0; k < 4; k++) {
                    int i2 = i + dx[k];
                    int j2 = j + dy[k];
                    if (i2 > 0 && i2 < H &&
                        j2 > 0 && j2 < W && s[i2][j2] == '#') {
                        found = true;
                    }
                }
                if (!found) ans = false;
            }
        }
    }
    cout << (ans ? "Yes" : "No") << endl;
	return 0;
}