CF617A.Elephant

An elephant decided to visit his friend. It turned out that the elephant's house is located at point 0 and his friend's house is located at point x(x > 0) of the coordinate line. In one step the elephant can move 1, 2, 3, 4 or 5 positions forward. Determine, what is the minimum number of steps he need to make in order to get to his friend's house.

一头大象决定去拜访他的朋友。结果发现，大象的家位于数轴上的点 0 处，而他朋友的家位于点 $x$（$x > 0$）处。大象每步可以向前移动 1、2、3、4 或 5 个单位距离。请确定：大象到达朋友家所需的最少步数是多少？

The first line of the input contains an integer x (1 ≤ x ≤ 1 000 000) — The coordinate of the friend's house.

输入的第一行包含一个整数 $x$（$1 ≤ x ≤ 1 000 000$）——朋友家的坐标。

Print the minimum number of steps that elephant needs to make to get from point 0 to point x.

输出大象从点 0 到达点 $x$ 所需的最少步数。

In the first sample the elephant needs to make one step of length 5 to reach the point x.

In the second sample the elephant can get to point x if he moves by 3, 5 and 4. There are other ways to get the optimal answer but the elephant cannot reach x in less than three moves.

在第一个样例中，大象需要走一步，步长为 5，才能到达点 $x$。

在第二个样例中，大象可以通过步长为 3、5 和 4 的三步移动到达点 $x$。虽然存在其他方式得到最优答案，但大象无法用少于三步到达 $x$。