H,W = map(int,input().split())
mat = [list(input()) for _ in range(H)]
ans = "Yes"
dx = [-1,0,1,0]
dy = [0,1,0,-1]
for i in range(W):
    for j in range(H):
        if mat[i][j] == "#":
            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]] == "#":
                        break
                    elif k == 3:
                        ans = "No"
                        break
print(ans)