#include <iostream>
#include <vector>
#include <string>

using namespace std;

void solve (int H, int W, vector<string>& S) {
    // 場所からできるだけデカいバツを書いていったとき、同じになるか？
    enum direction {
        left_up,
        left_down,
        right_up,
        right_down,
    };

    vector<vector<vector<int>>> maximum_stretch(H, vector<vector<int>>(W, vector<int>(4)));

    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (S[i][j] == '.') maximum_stretch[i][j][left_up] = -1;

            if (S[i][j] == '#') {
                if (i == 0 || j == 0) {
                    maximum_stretch[i][j][left_up] = 0;
                }
                else {
                    maximum_stretch[i][j][left_up] = maximum_stretch[i-1][j-1][left_up] + 1;
                }
            }
        }
    }

    for (int i = H-1; 0 <= i; i--) {
        for (int j = 0; j < W; j++) {
            if (S[i][j] == '.') maximum_stretch[i][j][left_down] = -1;

            if (S[i][j] == '#') {
                if (i == H-1 || j == 0) {
                    maximum_stretch[i][j][left_down] = 0;
                }
                else {
                    maximum_stretch[i][j][left_down] = maximum_stretch[i+1][j-1][left_down] + 1;
                }
            }
        }
    }

    for (int i = 0; i < H; i++) {
        for (int j = W-1; 0 <= j; j--) {
            if (S[i][j] == '.') maximum_stretch[i][j][right_up] = -1;

            if (S[i][j] == '#') {
                if (i == 0 || j == W-1) {
                    maximum_stretch[i][j][right_up] = 0;
                }
                else {
                    maximum_stretch[i][j][right_up] = maximum_stretch[i-1][j+1][right_up] + 1;
                }
            }
        }
    }

    for (int i = H-1; 0 <= i; i--) {
        for (int j = W-1; 0 <= j; j--) {
            if (S[i][j] == '.') maximum_stretch[i][j][right_down] = -1;

            if (S[i][j] == '#') {
                if (i == H-1 || j == W-1) {
                    maximum_stretch[i][j][right_down] = 0;
                }
                else {
                    maximum_stretch[i][j][right_down] = maximum_stretch[i+1][j+1][right_down] + 1;
                }
            }
        }
    }

    vector<string> T(H, string(W, 0));
    vector<vector<int>> draw_table(H, vector<int>(W));

    for (int i = 0; i < H; i++) for (int j = 0; j < W; j++) draw_table[i][j] = 0;
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (S[i][j] == '.') T[i][j] = '.';
            if (S[i][j] == '#') {
                int len = H*W;
                for (int k = 0; k < 4; k++) len = min(len, maximum_stretch[i][j][k]);

                if (len == 0) continue;
                draw_table[i-len][j-len] += 1;
                if (i+len+1 < H && j+len+1 < W) draw_table[i+len+1][j+len+1] += -1;
            }
        }
    }

    // 塗る
    for (int i = 0; i < H; i++) for (int j = 0; j < W; j++) {
        if (0 < i && 0 < j) draw_table[i][j] += draw_table[i-1][j-1];

        if (T[i][j] == '#') continue;
        if (0 < draw_table[i][j]) {
            T[i][j] = '#';
        }
        else {
            T[i][j] = '.';
        }
    }

    for (int i = 0; i < H; i++) for (int j = 0; j < W; j++) draw_table[i][j] = 0;
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (S[i][j] == '.') T[i][j] = '.';
            if (S[i][j] == '#') {
                int len = H*W;
                for (int k = 0; k < 4; k++) len = min(len, maximum_stretch[i][j][k]);

                if (len == 0) continue;
                draw_table[i+len][j-len] += 1;
                if (0 <= i-len-1 && j+len+1 < W) draw_table[i-len-1][j+len+1] += -1;
            }
        }
    }

    // 塗る
    for (int i = H-1; 0 <= i; i--) for (int j = 0; j < W; j++) {
        if (i < H-1 && 0 < j) draw_table[i][j] += draw_table[i+1][j-1];

        if (T[i][j] == '#') continue;
        if (0 < draw_table[i][j]) {
            T[i][j] = '#';
        }
        else {
            T[i][j] = '.';
        }
    }

    bool ok = true;
    for (int i = 0; i < H; i++) for (int j = 0; j < W; j++) if (S[i][j] != T[i][j]) ok = false;

    /* visualize
    for (int k = 0; k < 4; k++) {
        for (int i = 0; i < H; i++) {
            for (int j = 0; j < W; j++) {
                cout << maximum_stretch[i][j][k] << " ";
            }
            cout << "\n";
        }
        cout << "\n";
    }
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            cout << T[i][j];
        }
        cout << "\n";
    }
    // */


    if (ok) {
        cout << "Yes\n";
    }
    else {
        cout << "No\n";
    }
}

int main () {
    int H, W; cin >> H >> W;
    vector<string> S(H);
    for (int i = 0; i < H; i++) cin >> S[i];

    solve(H, W, S);
}