s = []
ok = True

for i in range(3):
    s.append(input())
    for j in range(3):
        if i != 0 and s[i - 1][j] == s[i][j]:
            ok = False
        # end
        if j != 0 and s[i][j - 1] == s[i][j]:
            ok = False
        # end
    # end
# end

if ok:
    print("Yes")
else:
    print("No")
# end