H,W = map(int,input().split())
L = []
for i in range(H):
    L.append((input()))
for i in range(H):
    for j in range(W):
        if L[i][j] == "#":
            flag = False
            if i-1 >=0 and L[i-1][j] == "#":
                flag = True
            if i+1 <H and L[i+1][j] == "#":
                flag = True
            if j-1 >=0 and L[i][j-1] == "#":
                flag = True
            if j+1 <W and L[i][j+1] == "#":
                flag = True
            if flag == False:
                print("No")
                exit()
if flag:
    print("Yes") 