Problem Description

Takahashi is in the middle of moving. He has just finished packing all his belongings into cardboard boxes, and a truck has just arrived in front of his house. Takahashi needs to move all $ N $ cardboard boxes to the truck.

The cardboard boxes are very heavy, but Takahashi is strong and can carry one box in each hand. This means that during one round trip between his house and the truck, he can carry a maximum of two boxes at once.

Given the large number of boxes, Takahashi is wondering how many minimum round trips he needs to make to move all $ N $ boxes.

Input Format

The input is given from the standard input in the following format:

$ N $

• The first line contains an integer $ N $ ($1 \leq N \leq 1,000$), representing the number of cardboard boxes.

Output Format

Output the minimum number of round trips required to move all the cardboard boxes in one line.

Ensure a newline at the end of the output.

Sample Input and Output

Sample Input #1

2

Sample Output #1

1

Sample Input #2

5

Sample Output #2

3

Sample Input #3

1

Sample Output #3

1

Notes/Hints

Sample Explanation 1

Two boxes can be moved in one round trip.

Sample Explanation 2

For example, in the first two round trips, two boxes can be moved each time, and in the last round trip, the remaining one box can be moved.

Sample Explanation 3

Even if there is only one box, one round trip is necessary.

见题面 Input 部分

见题面 Output 部分