x = int(input())
floor = [-1 for i in range(x+1)]
for i in range(2,x+1):
  if floor[i] != -1:
    continue
  j = i
  while j <= x:
    if floor[j] == -1:
      floor[j] = i
    j += i
ans = 0
while x != 1:
  ans += floor[x]
  x //= floor[x]
print(ans)