a,b=map(int,input().split())
x=[0,0,-1,1]
y=[-1,1,0,0]
d=[[0]*a for x in range(b)]
for i in range(b):
    d[i]=list(input())
    
result="Yes"

for i in range(b):
    for j in range(a):
        if d[i][j] == '#':
            check=0
            for xv,yv in zip(x,y):
                if 0 <= xv + j < a  and 0 <= yv + i < b:
                    if d[i+yv][j+xv] == '#':
                        check=1
                        break
            if check==0:
                result="No"
                        
print(result)
