x = int(input())

curr = 0
n = 0
ans = 0
while curr != x:
    if n == 0 or n == 1 or n == 4:
        curr += 2
        ans += 2
    elif n == 2 or n == 3 or n == 5 or n == 6:
        curr -= 1
        ans += 1
    n = (n + 1) % 7
print(ans)