@staticmethod
def a():
    (s, e) = np.array(sys.stdin.read().split(), dtype=np.int16).reshape(3, 2).T
    print(((s // 10) * e).sum())
@staticmethod
def a():
    (s, e) = np.array(sys.stdin.read().split(), dtype=np.int16).reshape(3, 2).T
    print(((s // 10) * e).sum())