# No.888 約数の総和
n = int(input())
divisors = []

if n == 1:
    divisors = [1]
elif n < 4:
    divisors = [1, n]
else:
    divisors = [1, n]
    for i in range(2, n):
        if n % i == 0:
            divisors.append(i)

print(sum(divisors))