H,W = map(int,input().split())
s = [input() for i in range(H)]
dx=[0,-1,1,0]
dy=[1,0,0,-1]
flag = True
for i in range(W):
    for j in range(H):
        if s[i][j]=='#':
            cnt = 0
            for k in range(4):
                if 0<=j+dx[k] and j+dx[k]<H and 0<=i+dy[k] and i+dy[k]<W:
                    if s[i+dy[k]][j+dx[k]]=='#':
                        cnt += 1
            if cnt==0:
                flag=False
print('Yes' if flag else 'No')

