#include <stdio.h>
#include <iostream>
#include <string.h>

int h, w;

void print_array(int h, int w, int array[]) {
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            printf("%d", array[i * w + j]);
            if (j != w - 1) {
                printf(" ");
            }
        }
        printf("\n");
    }
}

int check_board(int size, int array[]) {
    for (int i = 0; i < size; i++) {
        if (array[i] != 0) {
            return 0;
        }
    }
    return 1;
}

int main(int, char **) {

    scanf("%d %d", &h, &w);

    int board[h * w];
    char s[w];

    for (int i = 0; i < h; i++) {
        scanf("%s", s);
        for (int j = 0; j < w; j++) {
            if (s[j] == '#') {
                board[i * w + j] = 1;
            } else {
                board[i * w + j] = 0;
            }
        }
    }
    // print_array(h, w, board);
    // printf("\n");
    if (check_board(h * w, board) == 1) {
        printf("NO\n");
        return 0;
    }

    for (int y = -h; y < h; y++){
        for (int x = -w; x < w; x++){
            int board_new[h * w];

            memcpy(board_new, board, sizeof(int) * h * w);

            for (int i = 0; i < h; i++){
                for (int j = 0; j < w; j++){
                    if ((i + y < h) && (j + x < w) && (i + y >= 0) && (j + x >= 0)) {
                        if ((board_new[i * w + j] == 1) && (board_new[(i + y) * w + (j + x)])) {
                            board_new[i * w + j] = 0;
                            board_new[(i + y) * w + (j + x)] = 0;
                        }
                    }
                }
            }
            // print_array(h, w, board_new);
            // printf("\n");
            if (check_board(h*w, board_new) == 1 && !(y == 0 && x == 0)) {
                printf("YES\n");
                return 0;
            }
        }
    }
    printf("NO\n");
    return 0;
}