import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
dx = [2,2,-1,-1,2,-1,-1]
x = ni()
y = 0
s = 0
for i in range(100):
    for j in dx:
        y += j
        s += abs(j)
        if y == x:
            print(s)
            exit()