def inner(x, y):
    return 0 <= x and x < W and 0 <= y and y < H

def ok(s):
    for i in range(H):
         for j in range(W):
             if s[i][j] == '#':
                 if inner(i-1, j) and s[i-1][j] == '#':
                     continue
                 if inner(i+1, j) and s[i+1][j] == '#':
                     continue
                 if inner(i, j-1) and s[i][j-1] == '#':
                     continue
                 if inner(i, j+1) and s[i][j+1] == '#':
                     continue
                 return 'No'
    return 'Yes'


H, W = map(int, input().split())
s = []
for i in range(H):
    s.append(input())
print(ok(s))