import sys
input = sys.stdin.readline

def make_divisors(n):
    lower_divisors , upper_divisors = [], []
    i = 1
    while i*i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n//i)
        i += 1
    return lower_divisors + upper_divisors[::-1]

N = int(input())
Y = make_divisors(N)
ans = 0
for y in Y:
    tmp = N//y
    if y==1:
        cnt = (tmp+1)//2-1
        #print(cnt)
        if cnt>0:
            ans += cnt
        else:
            break
    else:
        cnt = (tmp+y)//(y+1)-1
        #print(cnt)
        if cnt>0:
            ans += cnt
        else:
            break
print(ans)