H,W = map(int,input().split())
s = [input() for i in range(H)]
precount = 0
for i in range(H):
    precount += s[i].count("#")
if precount == 0:
    print("Yes")
else:
    ans = "Yes"
    dx = [1,0,-1,0]
    dy = [0,1,0,-1]
    for i in range(H):
        for j in range(W):
            if s[i][j] == "#":
               count = 0
               for k in range(4):
                   nx = j+dx[k]
                   ny = i+dy[k]
                   if 0 <= nx < W and 0 <= ny < H:
                      if s[ny][nx] == "#":
                         count += 1
               if count == 0:
                  ans = "No"

print(ans)