x = int(input())
n = 0
c = 0
#A → A → B → B → A → B → B
for i in range(100):
    n += 2
    c += 2
    if n == x:
        print(c)
        break
    n += 2
    c += 2
    if n == x:
        print(c)
        break
    n -= 1
    c += 1
    if n == x:
        print(c)
        break
    n -= 1
    c += 1
    if n == x:
        print(c)
        break
    n += 2
    c += 2
    if n == x:
        print(c)
        break
    n -= 1
    c += 1
    if n == x:
        print(c)
        break
    n -= 1
    c += 1
    if n == x:
        print(c)
        break