n,m=map(int,input().split())
l=[]
f=0
nf=0
for i in range(n):
    l.append(list(input()))
    
for i in range(n):
    for j in range(m):
        if l[i][j]=='#':
            if (i>0 and l[i-1][j]=='#') or (j>0 and l[i][j-1]=='#') or (i<n-1 and l[i+1][j]) or (j<n-1 and l[i][j+1]):
                f=0
            else:
                nf=1
if nf==1:
    print('No')
else:
    print('Yes')
            
              
                                                                                         