H,W = map(int,input().split())
mat = [list(input()) for _ in range(H)]
ans = "Yes"

def judge(i, j):
    dx = [-1, 0, 1, 0]
    dy = [0, 1, 0, -1]
    for k in range(4):
        if 0 <= i+dx[k] <= (W-1) and 0 <= j+dy[k] <= (H-1):
            if mat[i+dx[k]][j+dy[k]] == "#":
                return True
    return False

for i in range(W):
    for j in range(H):
        if mat[i][j] == "#":
            if not judge(i,j):
                ans = "No"
                break
print(ans)