def divisors(n):
    rt = int(n ** 0.5) + 1
    s = [False] * rt
    s[1] = True
    for x in range(2, rt):
        if n % x == 0:
            s[x] = True
    return (i for i in range(rt) if s[i])


def solve():
    N = int(input())

    g = N if N % 2 else N // 2

    s = 0
    for d in divisors(g):
        s += d
        e = g // d
        if e != d:
            s += e

    print(s)


if __name__ == '__main__':
    solve()