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

mx1 = [[0]*(W+2) for _ in range(H+2)]
mx2 = [[0]*(W+2) for _ in range(H+2)]
mx3 = [[0]*(W+2) for _ in range(H+2)]
mx4 = [[0]*(W+2) for _ in range(H+2)]

for i in range(H):
    for j in range(W):
        if S[i][j] == '#':
            mx1[i][j] = mx1[i-1][j-1] + 1
for i in range(H):
    for j in range(W):
        if S[i][j] == '#':
            mx2[i][j] = mx2[i-1][j+1] + 1
for i in range(H-1,-1,-1):
    for j in range(W):
        if S[i][j] == '#':
            mx3[i][j] = mx3[i+1][j-1] + 1
for i in range(H-1,-1,-1):
    for j in range(W):
        if S[i][j] == '#':
            mx4[i][j] = mx4[i+1][j+1] + 1

imos1 = [[0]*(W+2) for _ in range(H+2)]
imos2 = [[0]*(W+2) for _ in range(H+2)]

for i in range(H):
    for j in range(W):
        r = min(mx1[i][j], mx2[i][j], mx3[i][j], mx4[i][j]) - 1
        if r <= 0:
            continue
        imos1[i - r][j - r]+=1
        imos1[i + r + 1][j + r + 1]-=1
        imos2[i - r][j + r]+=1
        imos2[i + r + 1][j - r - 1]-=1

for i in range(H):
    for j in range(W):
        imos1[i][j] += imos1[i - 1][j - 1]
        imos2[i][j] += imos2[i - 1][j + 1]

same = True
for i in range(H):
    for j in range(W):
        if S[i][j] == '#' and imos1[i][j] + imos2[i][j] == 0:
            same = False

print("Yes" if same else "No")