@staticmethod
def d():
    n = int(sys.stdin.readline().rstrip())
    f = np.zeros((n + 1), dtype=np.int64)
    for i in range(1, (n + 1)):
        f[i::i] += 1
    print((np.arange(1, (n + 1)) * f[1:]).sum())
@staticmethod
def d():
    n = int(sys.stdin.readline().rstrip())
    f = np.zeros((n + 1), dtype=np.int64)
    for i in range(1, (n + 1)):
        f[i::i] += 1
    print((np.arange(1, (n + 1)) * f[1:]).sum())