H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]
l=[-1,1]
cnt=0
for i in range(H):
    for j in range(W):
        a=set()
        if s[i][j]=='#':
            cnt+=1
            for v in l:
                if H>i-v>=0:
                    a.add(s[i-v][j])
                if H>j-v>=0:
                    s[i][j-v]
                    a.add(s[i][j-v])
            if '#' not in a:
                print('No')
                exit()
if cnt==0:
    print('No')
else:
    print('Yes')