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

inpt =[]
for h in H:
    i = str(input())
    inpt.append(i)

string = 'No'

for h in range(H):
    for w in range(W):
        if h == H-1 or w == W-1:
            continue
        if inpt[h][w] == '#':
            if inpt[h+1][w] == '#' or inpt[h][w+1] == '#':
                 string = 'Yes'
                 
print(string)
