import sys
h,w = ri()
C = [input() for _ in range(h)]

dd = [(0,1),(0,-1),(1,0),(-1,0)]
for i in range(h):
    for j in range(w):
        if C[i][j] == '#':
            b = []
            for di,dj in dd:
                if 0<=i+di<h and 0<=j+dj<w:
                    b.append(C[i+di][j+dj] == '.')
            if all(b):
                print('No')
                sys.exit()
print('Yes')