H,W = map(int,input().split())
S = []
flag = "Yes"
for i in range(0,H):
    S.append(list(input()))

    
for i in range(0,H):
    for j in range(0,W):
        if S[i][j] == "#":
            if i != 0 and S[i-1][j] == "#" : continue
            elif i != H-1 and S[i+1][j] == "#": continue
            elif j != 0 and S[i][j-1] == "#": continue
            elif j != W-1 and S[i][j+1] == "#":continue
            else flag = "No"
            
print(flag)
          