import sys
h, w = map(int, input().split())
sq = []

for i in range(h):
    sq.append(input())

print(sq)

def is_valid(i, j):
    valid = False
    if i > 0 and sp[i-1][j] == '#':
        valid = True
    elif i < h-1 and sp[i+1][j] == '#':
        valid = True
    elif j > 0 and sp[i][j-1] == '#':
        valid = True
    elif j < w-1 and sp[i][j+1] == '#':
        valid = True
    return valid

for i in range(h):
    for j in range(w):
        #print(sq[i][j])
        c = sq[i][j]
        if c == '#':
            if not is_valid(i, j):
                print('No')
                sys.exit()

print('Yes')
