
H,W = map(int, input().split())
s = [input() for _ in range(H)]
import sys
for j in range(H):
    for i in range(W):
        if s[j][i] =='#':
            if 0<i and s[j][i-1] == '#':
                pass
            elif 0<j and s[j-1][i] == '#':
                pass
            elif i<H-1 and s[j][i+1] == '#':
                pass
            elif j<W-1 and s[j+1][i] == '#':
                pass
            else:
                print('No')
                sys.exit()
print('Yes')