H, W = map(int, input().split())
glid = [[i for i in input()] for i in range(H)]


for i in range(H):
    for j in range(W):
        if glid[i][j] == '#':

            if 0 <= i-1 and i+1 < H and 0 <= j-1 and j+1 < W:
                if glid[i-1][j] == glid[i][j-1] == glid[i][j+1] == glid[i+1][j] == '.':
                    print('No')
                    exit()
                else:
                    print('Yes')
                    exit()
