#ABC096 C - Grid Repainting 2
I = raw_input().split(" ")
H = int(I[0])
W = int(I[1])
A = [list(raw_input()) for i in range(W)]
ans = 0
for X in range(H):
    for Y in range(W):
        counter = 0
        if A[X][Y] == "#":
            if X != 0 and A[X][Y] == A[X - 1][Y]:
                counter += 1
            if X != H - 1 and A[X][Y] == A[X + 1][Y]:
                counter += 1
            if Y != 0 and A[X][Y] == A[X][Y - 1]:
                counter += 1
            if Y != W - 1 and A[X][Y] == A[X][Y + 1]:
                counter += 1
            if counter == 0:
                ans += 1
if ans == 0:
    print "Yes"
else:
    print "No"