l = input().split()
h,w = int(l[0]),int(l[1])
mapxy = []
for i in range(h):
    mapxy.append(list(input()))
dx = [1,0,-1,0]
dy = [0,1,0,-1]
flag1 = 0
flag2 = 0
for i in range(h):
    for j in range(w):
        if mapxy[i][j] == "#":
            for k in range(4):
                if 0<=i+dx[k]<w and 0<=j+dy[k]<h:
                    if mapxy[i+dx[k]][j+dy[k]] == "#":
                        flag1 = 1
            if flag1 == 0:
                flag2 = 1
                break
            flag1 = 0
    if flag2 == 1:
        print("No")
        break
if flag2 != 1:
    print("Yes")