H, W = map(int,input().split())
s = [list(input()) for _ in range(H)]
for i in range(H):
    s[i] = [0] + s[i] + [0]
s = [[0]*W] + s + [[0]*W]
for i in range(1,H+1):
    for j in range(1,W+1):
        if s[i][j] == '#':
            if s[i-1][j] == '#' or s[i][j-1] == '#' or s[i][j+1] == '#' or s[i+1][j] == '#':
                continue
            else:
                print('No')
                exit()
print('Yes')
