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.

Input

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

Output

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

Examples

Input

5

Output

1

Input

12

Output

3

Note

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.

問題分析：一開始以為跟老農(nóng)找奶牛一樣要用BFS進行探索，多看了幾次才發(fā)現(xiàn)有明顯不同，只要從大的步數(shù)開始掃就可以

AC代碼：

#include<iostream> using namespace std; int main() {int x;while (cin >> x){if (x % 5 == 0){cout << x / 5 << endl;}else{cout << x / 5 + 1 << endl;}} }

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