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

for i in range(W):
    A.append(input())

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

