H,W=map(int,input().split())
A=[]

for i in range(W):
    S='.'+input()+'.'
    A.append(S)
K='.'
A.insert(0,K*(W+2))
A.append(K*(W+2))

for i in range(1,H):
    for j in range(1,W):
        if A[i][j]=='#':
            if A[i+1][j]=='.' and A[i-1][j]=='.' and A[i][j+1]=='.' and A[i][j-1]=='.':
                print('No')
                exit(0)

print('Yes')
