import sys
H, W = map(int, input().split())
s = [input() for _ in range(H)]
print(s)
dx = [1, 0, -1, 0]
dy = [0, 1, 0, -1]
for i in range(H):
    for j in range(W):
        if s[i][j] == '#':
            for k in range(4):
                try:
                    if s[i + dy[k]][j + dx[k]] == '#':
                        flag = False
                        break
                    else:
                        flag = True
                except IndexError:
                    pass
            if flag:
                print('No')
                sys.exit()
print('Yes')
