import sys



x = int(sys.stdin.readline())

n = x // 11

r = x % 11

if r == 0:

    print((2*n))

elif r <= 6:

    print((2*n + 1))

else:

    print((2 * (n+1)))
import sys



x = int(sys.stdin.readline())



n = x // 11

r = x % 11

if r == 0:

    print((2*n))

elif r <= 6:

    print((2*n+1))

else:

    print((2*n+2))
import sys

x = int(sys.stdin.readline())
n = x // 11
r = x % 11
if r == 0:
    print((2 * n))
elif r <= 6:
    print((2 * n + 1))
else:
    print((2 * (n + 1)))

import sys

x = int(sys.stdin.readline())
n = x // 11
r = x % 11
if r == 0:
    print((2 * n))
elif r <= 6:
    print((2 * n + 1))
else:
    print((2 * n + 2))

-    print((2 * (n + 1))) +    print((2 * n + 2))