def main():
    x = int(input())

    d = [2, 2, -1, -1, 2, -1, -1]
    i = 0
    ans = 0
    while x != 0:
        x -= d[i]
        ans += abs(d[i])
        i = (i + 1) % 7
    print(ans)


if __name__ == "__main__":
    main()