H,W=map(int,input().split())
s=[]
s1=[[]for i in range(H)]
dir=[[-1,0],[1,0],[0,-1],[0,1]]
a=0
for i in range(H):
    s.append(input())
for i in range(H):
    for a in s[i]:
        s1[i].append(a)
for i in range(H):
    for j in range(W):
        c=0
        if s1[i][j]=='#':
            for k in dir:
                if i+k[0]>=0 and i+k[0]<H and j+k[1]>=0 and j+k[1]<W and s1[i+k[0]][j+k[1]]=='#':
                    c=1
                    break
        else:
            break
        if c==0:
            a=1
            break
    if a==1:
        break
if a==1:
    print('No')
else:
    print('Yes')
