H,W=map(int,input().split())
grid=[[0]*W for _ in range(H)]
for h in range(H):
    for w,s in enumerate(input().rstrip()):
        grid[h][w]=s

for h0 in range(-H,H):
    for w0 in range(-W,W):
        if (h0,w0)==(0,0):
            continue
        flg=0
        used=[[0]*W for _ in range(H)]
        for h in range(H):
            for w in range(W):
                if grid[h][w]==".":
                    continue
                if grid[h][w]=="#":
                    if used[h][w]==1:
                        continue
                    if not (h+h0<0 or w+w0<0 or h+h0>=H or w+w0>=W or grid[h+h0][w+w0]=="."):
                        used[h+h0][w+w0]=1
                        continue
                flg=1
                break
            if flg==1:
                break
        if flg==0:
            print("YES")
            exit()
print("NO")