H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]
cnt=0
for i in range(H):
    for j in range(W):
        if s[i][j]=='#':
            l=[[i-1,j],[i+1,j],[i,j-1],[i,j+1]]
            OK=0
            for v in l:
                if H>v[0]>=0 and W>v[1]>=0:
                    if s[v[0]][v[1]]=='#':
                        OK=1
            if OK==0:
                print('No')
                exit()
        else:
            cnt+=1
if cnt==H*W:
    print('No')
else:
    print('Yes')