H, W = map(int, input().split())
s = [list(input()) for _ in range(H)]
import sys


for i in range(H):
    for j in range(W):
        if s[i][j] == "#":
            flag = 0b0000
            if i > 0:
                if s[i-1][j] == "#":
                    flag |= 0b1000
                    break
            if j < W-1:
                if s[i][j + 1] == "#":
                    flag |= 0b0100
                    break
            if i < H-1:
                if s[i + 1][j] == "#":
                    flag |= 0b0010
                    break
            if j > 0:
                if s[i][j - 1] == "#":
                    flag |= 0b0001
                    break

            if flag & 0x0000 == 0:
                print("No")
                sys.exit(0)

print("Yes")
