val = input()
val = [int(x.strip()) for x in val.split(" ")]
h = val[0]
w = val[1]

s = [[0]*w]*h
for i in range(h):
    s[i] = input()

ans = "Yes"

for i in range(h):
    for j in range(w):
        d = 0
        if s[i][j] == ".":
            continue

        if i > 0:
            if s[i-1][j] == "#":
                d += 1

        if i < h-1:
            if s[i+1][j] == "#":
                d += 1

        if j > 0:
            if s[i][j-1] == "#":
                d += 1

        if j < h-1:
            if s[i][j+1] == "#":
                d += 1
        
        if d == 0:
            ans = "No"
            break
    if ans == "No":
        break

print(ans)
