from math import *
N = input()
if N == 1:
    print 1
elif N == 2:
    print 1
else:
    v = N if N%2 else N/2
    ans = 0
    sn = int(sqrt(v))
    for i in range(1,sn+1):
        if v % i == 0:
            if i*i == v:
                ans += i
            else:
                ans += i
                ans += v/i
    print ans