# 2020/01/01
# 解答かんにんぐ

from copy import deepcopy

h,w=map(int,input().split())
s=[list(input()) for _ in range(h)]


def check(x,y):
    g=deepcopy(s)
    flag=False
    for i in range(h):
        for j in range(w):
            if g[i][j] in ['.','R','B']:continue
            if i+y<0 or i+y>=h or j+x<0 or j+x>=w:return False
            if g[i][j]==g[i+y][j+x]=='#':
                flag=True
                g[i][j]='R'
                g[i+y][j+x]='B'
            else:return False
    return flag


for x in range(-w,w+1):
    for y in range(-h,h+1):
        if x==y==0:continue
        res=check(x,y)
        if res:
            print('YES')
            exit()
print('NO')