H,W=map(int,input().split())
S=[input() for i in range(H)]
ans="No"
for i in range(H):
    for j in range(W):
        if S[i][j]=='#':
            if i>0 and S[i-1][j]=='#':
                ans="Yes"
            if i<H-1 and S[i+1][j]=='#':
                ans="Yes"
            if j>0 and S[i][j-1]=='#':
                ans="Yes"
            if j<W-1 and S[i][j+1]='#':
                ans="Yes"
print(ans)