H, W = map(int, input().split())
s = [list(input()) for _ in range(H)]
flag = 0000
flagggg = True
for i in range(H):
    for j in range(W):
        if s[i][j] == "#":
            if i > 0:
                if s[i-1][j] == "#":
                    flag &= 1000
                    break
            if j < W-1:
                if s[i][j + 1] == "#":
                    flag &= 100
                    break
            if i < H-1:
                if s[i + 1][j] == "#":
                    flag &= 10
                    break
            if j > 0:
                if s[i][j - 1] == "#":
                    flag &= 1
                    break
            if flag & 1111 != 1111:
                flagggg = False
                break
    else:
        continue
    break
if flagggg:
    print("Yes")
else:
    print("No")