
def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a
  
def prod(n):
  result = 1
  for x in n:
    result *= x
  return result
  
a = prime_factorize(n)
b = [a.pop(-1)]

while prod(a) > prod(b):
  prev_result = prod(a) + prod(b)
  b.append(a.pop(0))

  if prev_result < prod(a) + prod(b):
    a.append(b.pop(-1))
    break
  
print(prod(a)-1 +prod(b)-1)
