def check_4(i,j):
    hi = [1,0,-1,0]
    wi = [0,-1,0,1] #↓←↑→
    for p in range(4):
        if 0 <= i+hi[p] < H and 0 <= j+wi[p] < W:
            if cambus[i+hi[p]][j+wi[p]] == '#':
                return True
    return False

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

for i in range(H):
    for j in range(W):
        if not check_4(i,j):
            print('No')
            exit()
print('Yes')

