import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        // 変数宣言
        final int PAGE = 2;
        int inputFromKeyBoad;
        int min;

        // 標準入力
        Scanner sc = new Scanner( System.in );
        inputFromKeyBoad = sc.nextInt();

        // 演算処理
        min = (inputFromKeyBoad / PAGE) + (inputFromKeyBoad % PAGE);

        // 出力
        System.out.println( min );
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz