h,w = map(int, input().split())
s = []
for i in range(w):
    s.append(str(input()))
    
flag = True
for i in range(h):
    for j in range(w):
        if s[i][j] == '#':
            check = False
            if i+1 < h:
                if s[i+1][j] == '#':
                    check = True
            if j+1 < w:
                if s[i][j+1] == '#':
                    check = True
            if i-1 >= 0:
                if s[i-1][j] == '#':
                    check = True
            if j-1 >= 0:
                if s[i][j-1] == '#':
                    check = True
            if check == False:
                flag = False
if flag:
    print('Yes')
else:
    print('No')