package zerojudgeb558;
import java.util.Scanner;
public class Zerojudgeb558 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()) {
int n = scanner.nextInt();
int a = 1,b = 1;
boolean f = (n%2==1);
for (int i = 1; i < n; i++) {
if (i%2==0) {
a=b+i;
}
else{
b=a+i;
}
}
if (f) {
System.out.println(a);
}
else {
System.out.println(b);
}
}
}
}