import java.util.Scanner; public class CountSum { public static int countSum1(int n){ int sum = 0; for(int i =1;i<=n;i++){ if(i%2==0) sum-=i; else sum+=i; } return sum; } public static void main(String[] args){ int n = 0; Scanner scanner = new Scanner(System.in); if(scanner.hasNextInt()){ n = scanner.nextInt(); if(n%2==0) return; System.out.println(countSum1(n)); }else return; } }
import java.util.Scanner; public class Test2 { public static int f(int n){ int sum=0; for(int i=0;i<n;i++){ if(i%2==0){
sum=sum-i; }else{
sum=sum+i; }
} return sum; } public static void main(String[] args) {
Scanner scanner=new Scanner(System.in); int a=scanner.nextInt(); System.out.println(f(a)); }
}