import sys

H, W = map(int, input().split())
S = [list(input()) for i in range(H)]
dx = [-1, 0, 1, 0]
dy = [0, -1, 0, 1]

for i in range(H):
    for j in range(W):
        if(S[i][j]=="."):
            continue
        exist = False
        for k in range(4):
            if(0<=i+dy[k]<H and 0<=j+dx[k]<W and S[i+dy[k]][j+dx[k]]=="#"):
                exist = True
        if(exist==False):
            print("No")
            sys.exit()     
if(exist==True):
    print("Yes")