import sys
input=sys.stdin.readline

H,W=map(int, input().split())
C = [[] for i in range(H)]

for h in range(H):
    C[h] = list(input().strip())
#print(*C)

for h in range(H):
    for w in range(W):
        if C[w][h] == "#":
            if h == 0 or (h>0 and C[h-1][w] == "."):
                if w == 0 or (w>0 and C[h][w-1] == "."):
                    if w == W-1 or (w<W-1 and C[h][w+1] == "."):
                        if h == H-1 or (h<H-1 and C[h+1][w] == "."):
                            print("No")
                            exit()
print("Yes")
