H, W = map(int, input().split())

field = []

for i in range(H):
  field.append(list(input()))
count = 0

for i in range(1,H+1):
    for j in range(1,W+1):
        if C[i][j]=='#'and'#'not in[C[i-1][j], C[i][j-1], C[i][j+1], C[i+1][j]]:
            print('No')
            exit()
print("Yes")