import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;

public class Main {
	public static void main(String args[]) {
		FastScanner scanner = new FastScanner();
		int h=scanner.nextInt();
		int w=scanner.nextInt();
		int g[][]=new int[h][w];
		for(int i=0;i<h;i++) {
			String s=scanner.next();
			for(int j=0;j<w;j++) {
				char c=s.charAt(j);
				if(c=='#') {
					g[i][j]++;
				}
			}
		}
		
		for(int dy=-h;dy<h;dy++) {
			for(int dx=-w;dx<w;dx++) {
				int g1[][]=deep_copys(g);
				outside:for(int i=0;i<h;i++) {
					for(int j=0;j<w;j++) {
						if(g1[i][j]==1) {
							int mx=j+dx;
							int my=i+dy;
							if(0<=mx&&mx<=w-1&&0<=my&&my<=h-1) {
								g1[i][j]--;
								g1[my][mx]++;
								if(g1[my][mx]!=2) {
									break outside;
								}
							}else {
								break outside;
							}
						}
					}
				}
				if(check(g1)) {
					System.out.println("YES");
					return;
				}
			}
		}
		System.out.println("NO");
	}
	
	private static boolean check(int[][] g1) {
		int cnt=0;
		for(int i=0;i<g1.length;i++) {
			for(int j=0;j<g1[0].length;j++) {
				if(g1[i][j]==1) {
					return false;
				}else if(g1[i][j]==0) {
					cnt++;
				}
			}
		}
		if(cnt==g1.length*g1[0].length) {
			return false;
		}
		return true;
	}

	private static int[] deep_copy(int[] array) {
		int[] newArray = new int[array.length];
		System.arraycopy(array, 0, newArray, 0, array.length);
		return newArray;
	}
	
	private static int[][] deep_copys(int[][] array) {
		int[][] newArray = new int[array.length][array[0].length];
		for (int i = 0; i < array.length; i++) {
			newArray[i] = new int[array[0].length];
			System.arraycopy(array[i], 0, newArray[i], 0, array[i].length);
		}
		return newArray;
	}
}


class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() { return Double.parseDouble(next());}
}