def solve(grid):
    for h0 in range(H):
        for w0 in range(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:
                return True
    return False


H,W=map(int,input().split())
grid=[[0]*W for _ in range(H)]
cnt=0
for h in range(H):
    for w,s in enumerate(input().rstrip()):
        grid[h][w]=s
        if s=="#":
            cnt+=1

if cnt==0:
    print("NO")
    exit()

res=0

res|=solve(grid)

for h in range(H):
    grid[h].reverse()

res|=solve(grid)

grid.reverse()

res|=solve(grid)

for h in range(H):
    grid[h].reverse()


res|=solve(grid)

print("YES" if res else "NO")