H,W = map(int,input().split())
s = [input() for i in range(H)]
ans = "No"
for i in range(1,W-1):
    for j in range(1,H-1):
        if s[i][j] == "#":
            if s[i][j-1] == "#" or s[i][j+1] == "#" or s[i+1][j] == "#" or s[i-1][j] == "#":
                ans = "Yes"

print(ans)