H, W = map(int, input().split())
s = []
for i in range(W):
    s.append(input().split())
print(s)
answer = 'No'

for ii in range(H-2):
    for jj in range(W-2):
        if s[ii][jj] + s[ii][jj-1] == '##':
            answer = 'Yes'

for jj in range(W-2):
    for ii in range(H-2):
        if s[ii][jj] + s[ii-1][jj] == '##':
            answer = 'Yes'

print(answer)
