program ARC068C
    implicit none
    integer(8)::x
    integer(8)::result=0
    read(5,*)x

    result=x/11
    result=result*2

    if(mod(x,11)>=7)then
        result=result+2
    else if(mod(x,11)/=0)then
        result=result+1
    end if

    print'(i0)',result
    
end program ARC068C