H, W = map(int, input().split())
S = [input().split() for i in range(H)]
F = [[0]*(W+2) for i in range(H+2)]
D = [(-1,0), (0,1), (0, -1), (1, 0)]

for i in range(H):
    for j in range(W):
        if S[i][j] == '#':
            for d in D:
                F[i+1+d][j+1+d] == '#'

print('Yes' if F[1:H+1][1:W+1] == S else 'No')