N=int(input())
if N%2==0:
    x=N//2
else:
    x=N

# xの約数の列挙
import math
xr=math.ceil(math.sqrt(x))

LIST=[]
for i in range(1,xr+1):
    if x%i==0:
        LIST.append(i)
        LIST.append(x//i)
ANS=0

for s in set(LIST):
    ANS+=s

print(ANS)