N, M = map(int, input().split())
a = []
tmp = []
for i in range(N):
    tmp = list(map(str,input().split()))
    a.append(list(tmp[0]))

for i in range(1,N+1):
    for j in range(1,M+1):
        if a[i][j] == '#':
            if a[i][j - 1] != '#' and a[i - 1][j] != '#' and a[i][j + 1] != '#' and a[i + 1][j] != '#':
                print("No")
                exit()
        else:
            pass

print("Yes")