import sys
 
N, M = map(int, input().split())
a = []
tmp = []
for i in range(N):
    tmp = list(map(str,input().split()))
    a.append(list(tmp[0]))
 
 
cpi = [-1,0,0,1]
cpj = [0,-1,1,0]
 
smFlag = False
 
for i in range(N):
    for j in range(M):
        if a[i][j] == '#':
            for x,y in zip(cpi,cpj):
                if N > i + x > -1 and M > j + y > -1:
                    if a[i+x][j+y] == '#':
                        smFlag = True
            if not smFlag:
                print('No')
                sys.exit(0)

print('Yes')