H,W = map(int,input().split())
s = [input() for _ in range(H)]
A = "No"

for i in range(1,H-1):
    for j in range(1,W-1):
        if s[i][j] == "#" and s[i-1][j] == "#" and s[i][j-1] == "#" and s[i+1][j] == "#" and s[i][j+1] == "#":
            A = "Yes"
print(A)