import sys

input = sys.stdin.readline





def main():

    x = int(eval(input()))

    ans = 2 * (x//11)

    r = x % 11

    if r > 6:

        ans += 2

    elif r > 0:

        ans += 1

    print(ans)





if __name__ == '__main__':

    main()

import sys

input = sys.stdin.readline





def main():

    x = int(eval(input()))

    d, m = divmod(x, 11)

    print((2*d + int(m > 6) + int(m > 0)))





if __name__ == '__main__':

    main()

import sys

input = sys.stdin.readline


def main():
    x = int(eval(input()))
    ans = 2 * (x // 11)
    r = x % 11
    if r > 6:
        ans += 2
    elif r > 0:
        ans += 1
    print(ans)


if __name__ == "__main__":
    main()

import sys

input = sys.stdin.readline


def main():
    x = int(eval(input()))
    d, m = divmod(x, 11)
    print((2 * d + int(m > 6) + int(m > 0)))


if __name__ == "__main__":
    main()

-    ans = 2 * (x // 11) -    r = x % 11 -    if r > 6: -        ans += 2 -    elif r > 0: -        ans += 1 -    print(ans) +    d, m = divmod(x, 11) +    print((2 * d + int(m > 6) + int(m > 0)))