import itertools
def abc(Y,X,N,p):
    for dy,dx in itertools.product(range(Y),range(-X+1,X)):
        if dy==dx==0:	continue
        N-=1
        for y,x in itertools.product(range(Y),range(X)):
            if not 0<=y+dy<Y:               continue
            if not 0<=x+dx<X:               continue
            if p[y][x]<=N:                  continue
            if p[y+dy][x+dx]<=N:            break
            p[y][x]=p[y+dy][x+dx]=N
        else:
            mx=max([max(pa) for pa in p ])
            if 0<mx<=N:
                return "YES"
    return "NO"



def main():
    Y,X=map(int,input().split())
    N=9999
    p=[[[0,N][c=='#'] for c in input()] for _ in range(Y)]
    print(abc(Y,X,N,p))

main()