#include <iostream>
#include <vector>
#include "../cxx-prettyprint/prettyprint.hpp"
using std::vector;

int main() {
    int H, W;
    std::cin >> H >> W;

    vector<vector<char>> s(H, vector<char>(W));
    vector<vector<bool>> black_bits(H, vector<bool>(W, false));
    for (int i = 0; i < H; i ++) {
        for (int j = 0; j < W; j++) {
            std::cin >> s[i][j];
            if (s[i][j] == '#') black_bits[i][j] = true;
        }
    }

    for (int i = 0; i < H; i ++) {
        for (int j = 0; j < W; j ++) {
            if (!black_bits[i][j]) continue;

            bool cond_up    = i > 0     && black_bits[i - 1][j];
            bool cond_down  = i < H - 1 && black_bits[i + 1][j];
            bool cond_left  = j > 0     && black_bits[i][j - 1];
            bool cond_right = j < W - 1 && black_bits[i][j + 1];

            if (!(cond_up || cond_down || cond_left || cond_right)) {
                std::cout << "No" << std::endl;
                return 0;
            }
        }
    }
    std::cout << "Yes" << std::endl;
}
